Update the entire codebase to use is null/is not null

samples/Mvc.Server/Controllers/AccountController.cs

@@ -154,7 +154,7 @@ namespace Mvc.Server.Controllers
         public async Task<IActionResult> ExternalLoginCallback(string returnUrl = null)
         {
             var info = await _signInManager.GetExternalLoginInfoAsync();
-            if (info == null)
+            if (info is null)
             {
                 return RedirectToAction(nameof(Login));
             }
@@ -194,7 +194,7 @@ namespace Mvc.Server.Controllers
             {
                 // Get the information about the user from the external login provider
                 var info = await _signInManager.GetExternalLoginInfoAsync();
-                if (info == null)
+                if (info is null)
                 {
                     return View("ExternalLoginFailure");
                 }
@@ -221,12 +221,12 @@ namespace Mvc.Server.Controllers
         [AllowAnonymous]
         public async Task<IActionResult> ConfirmEmail(string userId, string code)
         {
-            if (userId == null || code == null)
+            if (userId is null || code is null)
             {
                 return View("Error");
             }
             var user = await _userManager.FindByIdAsync(userId);
-            if (user == null)
+            if (user is null)
             {
                 return View("Error");
             }
@@ -253,7 +253,7 @@ namespace Mvc.Server.Controllers
             if (ModelState.IsValid)
             {
                 var user = await _userManager.FindByNameAsync(model.Email);
-                if (user == null || !(await _userManager.IsEmailConfirmedAsync(user)))
+                if (user is null || !(await _userManager.IsEmailConfirmedAsync(user)))
                 {
                     // Don't reveal that the user does not exist or is not confirmed
                     return View("ForgotPasswordConfirmation");
@@ -287,7 +287,7 @@ namespace Mvc.Server.Controllers
         [AllowAnonymous]
         public IActionResult ResetPassword(string code = null)
         {
-            return code == null ? View("Error") : View();
+            return code is null ? View("Error") : View();
         }
 
         //
@@ -302,7 +302,7 @@ namespace Mvc.Server.Controllers
                 return View(model);
             }
             var user = await _userManager.FindByNameAsync(model.Email);
-            if (user == null)
+            if (user is null)
             {
                 // Don't reveal that the user does not exist
                 return RedirectToAction(nameof(AccountController.ResetPasswordConfirmation), "Account");
@@ -332,7 +332,7 @@ namespace Mvc.Server.Controllers
         public async Task<ActionResult> SendCode(string returnUrl = null, bool rememberMe = false)
         {
             var user = await _signInManager.GetTwoFactorAuthenticationUserAsync();
-            if (user == null)
+            if (user is null)
             {
                 return View("Error");
             }
@@ -354,7 +354,7 @@ namespace Mvc.Server.Controllers
             }
 
             var user = await _signInManager.GetTwoFactorAuthenticationUserAsync();
-            if (user == null)
+            if (user is null)
             {
                 return View("Error");
             }
@@ -387,7 +387,7 @@ namespace Mvc.Server.Controllers
         {
             // Require that the user has already logged in via username/password or external login
             var user = await _signInManager.GetTwoFactorAuthenticationUserAsync();
-            if (user == null)
+            if (user is null)
             {
                 return View("Error");
             }

samples/Mvc.Server/Controllers/AuthorizationController.cs

@@ -62,7 +62,7 @@ namespace Mvc.Server
             // Retrieve the user principal stored in the authentication cookie.
             // If it can't be extracted, redirect the user to the login page.
             var result = await HttpContext.AuthenticateAsync(IdentityConstants.ApplicationScheme);
-            if (result == null || !result.Succeeded)
+            if (result is null || !result.Succeeded)
             {
                 // If the client application requested promptless authentication,
                 // return an error indicating that the user is not logged in.
@@ -110,7 +110,7 @@ namespace Mvc.Server
 
             // If a max_age parameter was provided, ensure that the cookie is not too old.
             // If it's too old, automatically redirect the user agent to the login page.
-            if (request.MaxAge != null && result.Properties?.IssuedUtc != null &&
+            if (request.MaxAge is not null && result.Properties?.IssuedUtc is not null &&
                 DateTimeOffset.UtcNow - result.Properties.IssuedUtc > TimeSpan.FromSeconds(request.MaxAge.Value))
             {
                 if (request.HasPrompt(Prompts.None))
@@ -179,7 +179,7 @@ namespace Mvc.Server
                     // Automatically create a permanent authorization to avoid requiring explicit consent
                     // for future authorization or token requests containing the same scopes.
                     var authorization = authorizations.LastOrDefault();
-                    if (authorization == null)
+                    if (authorization is null)
                     {
                         authorization = await _authorizationManager.CreateAsync(
                             principal: principal,
@@ -269,7 +269,7 @@ namespace Mvc.Server
             // Automatically create a permanent authorization to avoid requiring explicit consent
             // for future authorization or token requests containing the same scopes.
             var authorization = authorizations.LastOrDefault();
-            if (authorization == null)
+            if (authorization is null)
             {
                 authorization = await _authorizationManager.CreateAsync(
                     principal: principal,
@@ -433,7 +433,7 @@ namespace Mvc.Server
             if (request.IsPasswordGrantType())
             {
                 var user = await _userManager.FindByNameAsync(request.Username);
-                if (user == null)
+                if (user is null)
                 {
                     return Forbid(
                         authenticationSchemes: OpenIddictServerAspNetCoreDefaults.AuthenticationScheme,
@@ -484,7 +484,7 @@ namespace Mvc.Server
                 // when the user password/roles change, use the following line instead:
                 // var user = _signInManager.ValidateSecurityStampAsync(info.Principal);
                 var user = await _userManager.GetUserAsync(principal);
-                if (user == null)
+                if (user is null)
                 {
                     return Forbid(
                         authenticationSchemes: OpenIddictServerAspNetCoreDefaults.AuthenticationScheme,

samples/Mvc.Server/Controllers/ErrorController.cs

@@ -18,7 +18,7 @@ namespace Mvc.Server
             // If the error was not caused by an invalid
             // OIDC request, display a generic error page.
             var response = HttpContext.GetOpenIddictServerResponse();
-            if (response == null)
+            if (response is null)
             {
                 return View(new ErrorViewModel());
             }

samples/Mvc.Server/Controllers/ManageController.cs

@@ -67,7 +67,7 @@ namespace Mvc.Server.Controllers
         {
             ManageMessageId? message = ManageMessageId.Error;
             var user = await GetCurrentUserAsync();
-            if (user != null)
+            if (user is not null)
             {
                 var result = await _userManager.RemoveLoginAsync(user, account.LoginProvider, account.ProviderKey);
                 if (result.Succeeded)
@@ -110,7 +110,7 @@ namespace Mvc.Server.Controllers
         public async Task<IActionResult> EnableTwoFactorAuthentication()
         {
             var user = await GetCurrentUserAsync();
-            if (user != null)
+            if (user is not null)
             {
                 await _userManager.SetTwoFactorEnabledAsync(user, true);
                 await _signInManager.SignInAsync(user, isPersistent: false);
@@ -126,7 +126,7 @@ namespace Mvc.Server.Controllers
         public async Task<IActionResult> DisableTwoFactorAuthentication()
         {
             var user = await GetCurrentUserAsync();
-            if (user != null)
+            if (user is not null)
             {
                 await _userManager.SetTwoFactorEnabledAsync(user, false);
                 await _signInManager.SignInAsync(user, isPersistent: false);
@@ -142,7 +142,7 @@ namespace Mvc.Server.Controllers
         {
             var code = await _userManager.GenerateChangePhoneNumberTokenAsync(await GetCurrentUserAsync(), phoneNumber);
             // Send an SMS to verify the phone number
-            return phoneNumber == null ? View("Error") : View(new VerifyPhoneNumberViewModel { PhoneNumber = phoneNumber });
+            return phoneNumber is null ? View("Error") : View(new VerifyPhoneNumberViewModel { PhoneNumber = phoneNumber });
         }
 
         //
@@ -156,7 +156,7 @@ namespace Mvc.Server.Controllers
                 return View(model);
             }
             var user = await GetCurrentUserAsync();
-            if (user != null)
+            if (user is not null)
             {
                 var result = await _userManager.ChangePhoneNumberAsync(user, model.PhoneNumber, model.Code);
                 if (result.Succeeded)
@@ -177,7 +177,7 @@ namespace Mvc.Server.Controllers
         public async Task<IActionResult> RemovePhoneNumber()
         {
             var user = await GetCurrentUserAsync();
-            if (user != null)
+            if (user is not null)
             {
                 var result = await _userManager.SetPhoneNumberAsync(user, null);
                 if (result.Succeeded)
@@ -208,7 +208,7 @@ namespace Mvc.Server.Controllers
                 return View(model);
             }
             var user = await GetCurrentUserAsync();
-            if (user != null)
+            if (user is not null)
             {
                 var result = await _userManager.ChangePasswordAsync(user, model.OldPassword, model.NewPassword);
                 if (result.Succeeded)
@@ -243,7 +243,7 @@ namespace Mvc.Server.Controllers
             }
 
             var user = await GetCurrentUserAsync();
-            if (user != null)
+            if (user is not null)
             {
                 var result = await _userManager.AddPasswordAsync(user, model.NewPassword);
                 if (result.Succeeded)
@@ -267,13 +267,13 @@ namespace Mvc.Server.Controllers
                 : message == ManageMessageId.Error ? "An error has occurred."
                 : "";
             var user = await GetCurrentUserAsync();
-            if (user == null)
+            if (user is null)
             {
                 return View("Error");
             }
             var userLogins = await _userManager.GetLoginsAsync(user);
             var otherLogins = (await _signInManager.GetExternalAuthenticationSchemesAsync()).Where(auth => userLogins.All(ul => auth.Name != ul.LoginProvider)).ToList();
-            ViewData["ShowRemoveButton"] = user.PasswordHash != null || userLogins.Count > 1;
+            ViewData["ShowRemoveButton"] = user.PasswordHash is not null || userLogins.Count > 1;
             return View(new ManageLoginsViewModel
             {
                 CurrentLogins = userLogins,
@@ -299,12 +299,12 @@ namespace Mvc.Server.Controllers
         public async Task<ActionResult> LinkLoginCallback()
         {
             var user = await GetCurrentUserAsync();
-            if (user == null)
+            if (user is null)
             {
                 return View("Error");
             }
             var info = await _signInManager.GetExternalLoginInfoAsync(await _userManager.GetUserIdAsync(user));
-            if (info == null)
+            if (info is null)
             {
                 return RedirectToAction(nameof(ManageLogins), new { Message = ManageMessageId.Error });
             }

samples/Mvc.Server/Controllers/ResourceController.cs

@@ -40,7 +40,7 @@ namespace Mvc.Server.Controllers
             }
 
             var user = await _userManager.GetUserAsync(User);
-            if (user == null)
+            if (user is null)
             {
                 return Challenge(
                     authenticationSchemes: OpenIddictValidationAspNetCoreDefaults.AuthenticationScheme,

samples/Mvc.Server/Controllers/UserinfoController.cs

@@ -26,7 +26,7 @@ namespace Mvc.Server.Controllers
         public async Task<IActionResult> Userinfo()
         {
             var user = await _userManager.GetUserAsync(User);
-            if (user == null)
+            if (user is null)
             {
                 return Challenge(
                     authenticationSchemes: OpenIddictServerAspNetCoreDefaults.AuthenticationScheme,

samples/Mvc.Server/Helpers/AsyncEnumerableExtensions.cs

@@ -8,7 +8,7 @@ namespace Mvc.Server.Helpers
     {
         public static Task<List<T>> ToListAsync<T>(this IAsyncEnumerable<T> source)
         {
-            if (source == null)
+            if (source is null)
             {
                 throw new ArgumentNullException(nameof(source));
             }

samples/Mvc.Server/Worker.cs

@@ -30,7 +30,7 @@ namespace Mvc.Server
             {
                 var manager = provider.GetRequiredService<IOpenIddictApplicationManager>();
 
-                if (await manager.FindByClientIdAsync("mvc") == null)
+                if (await manager.FindByClientIdAsync("mvc") is null)
                 {
                     await manager.CreateAsync(new OpenIddictApplicationDescriptor
                     {
@@ -74,7 +74,7 @@ namespace Mvc.Server
                 // * Scope: openid email profile roles
                 // * Grant type: authorization code
                 // * Request access token locally: yes
-                if (await manager.FindByClientIdAsync("postman") == null)
+                if (await manager.FindByClientIdAsync("postman") is null)
                 {
                     await manager.CreateAsync(new OpenIddictApplicationDescriptor
                     {
@@ -106,7 +106,7 @@ namespace Mvc.Server
             {
                 var manager = provider.GetRequiredService<IOpenIddictScopeManager>();
 
-                if (await manager.FindByNameAsync("demo_api") == null)
+                if (await manager.FindByNameAsync("demo_api") is null)
                 {
                     await manager.CreateAsync(new OpenIddictScopeDescriptor
                     {

shared/OpenIddict.Extensions/Helpers/OpenIddictHelpers.cs

@@ -27,12 +27,12 @@ namespace OpenIddict.Extensions
         /// <returns>A <see cref="Type"/> instance if the base type was found, <c>null</c> otherwise.</returns>
         public static IEnumerable<Type> FindGenericBaseTypes(Type type, Type definition)
         {
-            if (type == null)
+            if (type is null)
             {
                 throw new ArgumentNullException(nameof(type));
             }
 
-            if (definition == null)
+            if (definition is null)
             {
                 throw new ArgumentNullException(nameof(definition));
             }
@@ -60,7 +60,7 @@ namespace OpenIddict.Extensions
 
             else
             {
-                for (var candidate = type; candidate != null; candidate = candidate.BaseType)
+                for (var candidate = type; candidate is not null; candidate = candidate.BaseType)
                 {
                     if (!candidate.IsGenericType && !candidate.IsConstructedGenericType)
                     {

src/OpenIddict.Abstractions/OpenIddictExtensions.cs

@@ -21,7 +21,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictBuilder"/>.</returns>
         public static OpenIddictBuilder AddOpenIddict(this IServiceCollection services)
         {
-            if (services == null)
+            if (services is null)
             {
                 throw new ArgumentNullException(nameof(services));
             }
@@ -38,12 +38,12 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="IServiceCollection"/>.</returns>
         public static IServiceCollection AddOpenIddict(this IServiceCollection services, Action<OpenIddictBuilder> configuration)
         {
-            if (services == null)
+            if (services is null)
             {
                 throw new ArgumentNullException(nameof(services));
             }
 
-            if (configuration == null)
+            if (configuration is null)
             {
                 throw new ArgumentNullException(nameof(configuration));
             }

src/OpenIddict.Abstractions/Primitives/OpenIddictConverter.cs

@@ -23,7 +23,7 @@ namespace OpenIddict.Abstractions
         /// <returns><c>true</c> if the type is supported, <c>false</c> otherwise.</returns>
         public override bool CanConvert(Type typeToConvert)
         {
-            if (typeToConvert == null)
+            if (typeToConvert is null)
             {
                 throw new ArgumentNullException(nameof(typeToConvert));
             }
@@ -42,7 +42,7 @@ namespace OpenIddict.Abstractions
         /// <returns>The deserialized <see cref="OpenIddictMessage"/> instance.</returns>
         public override OpenIddictMessage Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
         {
-            if (typeToConvert == null)
+            if (typeToConvert is null)
             {
                 throw new ArgumentNullException(nameof(typeToConvert));
             }
@@ -51,7 +51,7 @@ namespace OpenIddict.Abstractions
 
             return typeToConvert == typeof(OpenIddictMessage)  ? new OpenIddictMessage(document.RootElement.Clone()) :
                    typeToConvert == typeof(OpenIddictRequest)  ? new OpenIddictRequest(document.RootElement.Clone()) :
-                   typeToConvert == typeof(OpenIddictResponse) ? (OpenIddictMessage) new OpenIddictResponse(document.RootElement.Clone()) :
+                   typeToConvert == typeof(OpenIddictResponse) ? new OpenIddictResponse(document.RootElement.Clone()) :
                    throw new ArgumentException(SR.GetResourceString(SR.ID1175), nameof(typeToConvert));
         }
 
@@ -63,12 +63,12 @@ namespace OpenIddict.Abstractions
         /// <param name="options">The JSON serializer options.</param>
         public override void Write(Utf8JsonWriter writer, OpenIddictMessage value, JsonSerializerOptions options)
         {
-            if (writer == null)
+            if (writer is null)
             {
                 throw new ArgumentNullException(nameof(writer));
             }
 
-            if (value == null)
+            if (value is null)
             {
                 throw new ArgumentNullException(nameof(value));
             }

src/OpenIddict.Abstractions/Primitives/OpenIddictExtensions.cs

@@ -31,7 +31,7 @@ namespace OpenIddict.Abstractions
         /// <param name="request">The <see cref="OpenIddictRequest"/> instance.</param>
         public static ImmutableArray<string> GetAcrValues(this OpenIddictRequest request)
         {
-            if (request == null)
+            if (request is null)
             {
                 throw new ArgumentNullException(nameof(request));
             }
@@ -45,7 +45,7 @@ namespace OpenIddict.Abstractions
         /// <param name="request">The <see cref="OpenIddictRequest"/> instance.</param>
         public static ImmutableArray<string> GetPrompts(this OpenIddictRequest request)
         {
-            if (request == null)
+            if (request is null)
             {
                 throw new ArgumentNullException(nameof(request));
             }
@@ -59,7 +59,7 @@ namespace OpenIddict.Abstractions
         /// <param name="request">The <see cref="OpenIddictRequest"/> instance.</param>
         public static ImmutableArray<string> GetResponseTypes(this OpenIddictRequest request)
         {
-            if (request == null)
+            if (request is null)
             {
                 throw new ArgumentNullException(nameof(request));
             }
@@ -73,7 +73,7 @@ namespace OpenIddict.Abstractions
         /// <param name="request">The <see cref="OpenIddictRequest"/> instance.</param>
         public static ImmutableArray<string> GetScopes(this OpenIddictRequest request)
         {
-            if (request == null)
+            if (request is null)
             {
                 throw new ArgumentNullException(nameof(request));
             }
@@ -88,7 +88,7 @@ namespace OpenIddict.Abstractions
         /// <param name="value">The component to look for in the parameter.</param>
         public static bool HasAcrValue(this OpenIddictRequest request, string value)
         {
-            if (request == null)
+            if (request is null)
             {
                 throw new ArgumentNullException(nameof(request));
             }
@@ -108,7 +108,7 @@ namespace OpenIddict.Abstractions
         /// <param name="prompt">The component to look for in the parameter.</param>
         public static bool HasPrompt(this OpenIddictRequest request, string prompt)
         {
-            if (request == null)
+            if (request is null)
             {
                 throw new ArgumentNullException(nameof(request));
             }
@@ -128,7 +128,7 @@ namespace OpenIddict.Abstractions
         /// <param name="type">The component to look for in the parameter.</param>
         public static bool HasResponseType(this OpenIddictRequest request, string type)
         {
-            if (request == null)
+            if (request is null)
             {
                 throw new ArgumentNullException(nameof(request));
             }
@@ -148,7 +148,7 @@ namespace OpenIddict.Abstractions
         /// <param name="scope">The component to look for in the parameter.</param>
         public static bool HasScope(this OpenIddictRequest request, string scope)
         {
-            if (request == null)
+            if (request is null)
             {
                 throw new ArgumentNullException(nameof(request));
             }
@@ -169,7 +169,7 @@ namespace OpenIddict.Abstractions
         /// <returns><c>true</c> if the request is a response_type=none request, <c>false</c> otherwise.</returns>
         public static bool IsNoneFlow(this OpenIddictRequest request)
         {
-            if (request == null)
+            if (request is null)
             {
                 throw new ArgumentNullException(nameof(request));
             }
@@ -196,7 +196,7 @@ namespace OpenIddict.Abstractions
         /// <returns><c>true</c> if the request is a code flow request, <c>false</c> otherwise.</returns>
         public static bool IsAuthorizationCodeFlow(this OpenIddictRequest request)
         {
-            if (request == null)
+            if (request is null)
             {
                 throw new ArgumentNullException(nameof(request));
             }
@@ -224,7 +224,7 @@ namespace OpenIddict.Abstractions
         /// <returns><c>true</c> if the request is an implicit flow request, <c>false</c> otherwise.</returns>
         public static bool IsImplicitFlow(this OpenIddictRequest request)
         {
-            if (request == null)
+            if (request is null)
             {
                 throw new ArgumentNullException(nameof(request));
             }
@@ -278,7 +278,7 @@ namespace OpenIddict.Abstractions
         /// <returns><c>true</c> if the request is an hybrid flow request, <c>false</c> otherwise.</returns>
         public static bool IsHybridFlow(this OpenIddictRequest request)
         {
-            if (request == null)
+            if (request is null)
             {
                 throw new ArgumentNullException(nameof(request));
             }
@@ -345,7 +345,7 @@ namespace OpenIddict.Abstractions
         /// </returns>
         public static bool IsFragmentResponseMode(this OpenIddictRequest request)
         {
-            if (request == null)
+            if (request is null)
             {
                 throw new ArgumentNullException(nameof(request));
             }
@@ -378,7 +378,7 @@ namespace OpenIddict.Abstractions
         /// </returns>
         public static bool IsQueryResponseMode(this OpenIddictRequest request)
         {
-            if (request == null)
+            if (request is null)
             {
                 throw new ArgumentNullException(nameof(request));
             }
@@ -410,7 +410,7 @@ namespace OpenIddict.Abstractions
         /// </returns>
         public static bool IsFormPostResponseMode(this OpenIddictRequest request)
         {
-            if (request == null)
+            if (request is null)
             {
                 throw new ArgumentNullException(nameof(request));
             }
@@ -426,7 +426,7 @@ namespace OpenIddict.Abstractions
         /// <returns><c>true</c> if the request is a code grant request, <c>false</c> otherwise.</returns>
         public static bool IsAuthorizationCodeGrantType(this OpenIddictRequest request)
         {
-            if (request == null)
+            if (request is null)
             {
                 throw new ArgumentNullException(nameof(request));
             }
@@ -442,7 +442,7 @@ namespace OpenIddict.Abstractions
         /// <returns><c>true</c> if the request is a client credentials grant request, <c>false</c> otherwise.</returns>
         public static bool IsClientCredentialsGrantType(this OpenIddictRequest request)
         {
-            if (request == null)
+            if (request is null)
             {
                 throw new ArgumentNullException(nameof(request));
             }
@@ -458,7 +458,7 @@ namespace OpenIddict.Abstractions
         /// <returns><c>true</c> if the request is a device code grant request, <c>false</c> otherwise.</returns>
         public static bool IsDeviceCodeGrantType(this OpenIddictRequest request)
         {
-            if (request == null)
+            if (request is null)
             {
                 throw new ArgumentNullException(nameof(request));
             }
@@ -474,7 +474,7 @@ namespace OpenIddict.Abstractions
         /// <returns><c>true</c> if the request is a password grant request, <c>false</c> otherwise.</returns>
         public static bool IsPasswordGrantType(this OpenIddictRequest request)
         {
-            if (request == null)
+            if (request is null)
             {
                 throw new ArgumentNullException(nameof(request));
             }
@@ -490,7 +490,7 @@ namespace OpenIddict.Abstractions
         /// <returns><c>true</c> if the request is a refresh token grant request, <c>false</c> otherwise.</returns>
         public static bool IsRefreshTokenGrantType(this OpenIddictRequest request)
         {
-            if (request == null)
+            if (request is null)
             {
                 throw new ArgumentNullException(nameof(request));
             }
@@ -505,7 +505,7 @@ namespace OpenIddict.Abstractions
         /// <returns>The destinations associated with the claim.</returns>
         public static ImmutableArray<string> GetDestinations(this Claim claim)
         {
-            if (claim == null)
+            if (claim is null)
             {
                 throw new ArgumentNullException(nameof(claim));
             }
@@ -529,7 +529,7 @@ namespace OpenIddict.Abstractions
         /// <param name="destination">The required destination.</param>
         public static bool HasDestination(this Claim claim, string destination)
         {
-            if (claim == null)
+            if (claim is null)
             {
                 throw new ArgumentNullException(nameof(claim));
             }
@@ -557,7 +557,7 @@ namespace OpenIddict.Abstractions
         /// <param name="destinations">The destinations.</param>
         public static Claim SetDestinations(this Claim claim, ImmutableArray<string> destinations)
         {
-            if (claim == null)
+            if (claim is null)
             {
                 throw new ArgumentNullException(nameof(claim));
             }
@@ -607,7 +607,7 @@ namespace OpenIddict.Abstractions
         /// <returns>The destinations, returned as a flattened dictionary.</returns>
         public static ImmutableDictionary<string, string[]> GetDestinations(this ClaimsPrincipal principal)
         {
-            if (principal == null)
+            if (principal is null)
             {
                 throw new ArgumentNullException(nameof(principal));
             }
@@ -645,12 +645,12 @@ namespace OpenIddict.Abstractions
         /// <returns>The principal.</returns>
         public static ClaimsPrincipal SetDestinations(this ClaimsPrincipal principal, ImmutableDictionary<string, string[]> destinations)
         {
-            if (principal == null)
+            if (principal is null)
             {
                 throw new ArgumentNullException(nameof(principal));
             }
 
-            if (destinations == null)
+            if (destinations is null)
             {
                 throw new ArgumentNullException(nameof(destinations));
             }
@@ -676,12 +676,12 @@ namespace OpenIddict.Abstractions
         /// </param>
         public static ClaimsIdentity Clone(this ClaimsIdentity identity, Func<Claim, bool> filter)
         {
-            if (identity == null)
+            if (identity is null)
             {
                 throw new ArgumentNullException(nameof(identity));
             }
 
-            if (filter == null)
+            if (filter is null)
             {
                 throw new ArgumentNullException(nameof(filter));
             }
@@ -698,7 +698,7 @@ namespace OpenIddict.Abstractions
                 }
             }
 
-            if (clone.Actor != null)
+            if (clone.Actor is not null)
             {
                 clone.Actor = clone.Actor.Clone(filter);
             }
@@ -716,12 +716,12 @@ namespace OpenIddict.Abstractions
         /// </param>
         public static ClaimsPrincipal Clone(this ClaimsPrincipal principal, Func<Claim, bool> filter)
         {
-            if (principal == null)
+            if (principal is null)
             {
                 throw new ArgumentNullException(nameof(principal));
             }
 
-            if (filter == null)
+            if (filter is null)
             {
                 throw new ArgumentNullException(nameof(filter));
             }
@@ -744,7 +744,7 @@ namespace OpenIddict.Abstractions
         /// <param name="value">The value associated with the claim.</param>
         public static ClaimsIdentity AddClaim(this ClaimsIdentity identity, string type, string value)
         {
-            if (identity == null)
+            if (identity is null)
             {
                 throw new ArgumentNullException(nameof(identity));
             }
@@ -772,7 +772,7 @@ namespace OpenIddict.Abstractions
         /// <param name="destinations">The destinations associated with the claim.</param>
         public static ClaimsIdentity AddClaim(this ClaimsIdentity identity, string type, string value, ImmutableArray<string> destinations)
         {
-            if (identity == null)
+            if (identity is null)
             {
                 throw new ArgumentNullException(nameof(identity));
             }
@@ -787,11 +787,6 @@ namespace OpenIddict.Abstractions
                 throw new ArgumentException(SR.GetResourceString(SR.ID1184), nameof(value));
             }
 
-            if (destinations == null)
-            {
-                throw new ArgumentNullException(nameof(destinations));
-            }
-
             identity.AddClaim(new Claim(type, value).SetDestinations(destinations));
             return identity;
         }
@@ -814,7 +809,7 @@ namespace OpenIddict.Abstractions
         /// <returns>The claim value.</returns>
         public static string? GetClaim(this ClaimsIdentity identity, string type)
         {
-            if (identity == null)
+            if (identity is null)
             {
                 throw new ArgumentNullException(nameof(identity));
             }
@@ -835,7 +830,7 @@ namespace OpenIddict.Abstractions
         /// <returns>The claim value.</returns>
         public static string? GetClaim(this ClaimsPrincipal principal, string type)
         {
-            if (principal == null)
+            if (principal is null)
             {
                 throw new ArgumentNullException(nameof(principal));
             }
@@ -856,7 +851,7 @@ namespace OpenIddict.Abstractions
         /// <returns>The claim values.</returns>
         public static ImmutableArray<string> GetClaims(this ClaimsIdentity identity, string type)
         {
-            if (identity == null)
+            if (identity is null)
             {
                 throw new ArgumentNullException(nameof(identity));
             }
@@ -877,7 +872,7 @@ namespace OpenIddict.Abstractions
         /// <returns><c>true</c> if the identity contains at least one claim of the specified type.</returns>
         public static bool HasClaim(this ClaimsIdentity identity, string type)
         {
-            if (identity == null)
+            if (identity is null)
             {
                 throw new ArgumentNullException(nameof(identity));
             }
@@ -898,7 +893,7 @@ namespace OpenIddict.Abstractions
         /// <returns>The claim values.</returns>
         public static ImmutableArray<string> GetClaims(this ClaimsPrincipal principal, string type)
         {
-            if (principal == null)
+            if (principal is null)
             {
                 throw new ArgumentNullException(nameof(principal));
             }
@@ -919,7 +914,7 @@ namespace OpenIddict.Abstractions
         /// <returns><c>true</c> if the principal contains at least one claim of the specified type.</returns>
         public static bool HasClaim(this ClaimsPrincipal principal, string type)
         {
-            if (principal == null)
+            if (principal is null)
             {
                 throw new ArgumentNullException(nameof(principal));
             }
@@ -940,7 +935,7 @@ namespace OpenIddict.Abstractions
         /// <returns>The claims identity.</returns>
         public static ClaimsIdentity RemoveClaims(this ClaimsIdentity identity, string type)
         {
-            if (identity == null)
+            if (identity is null)
             {
                 throw new ArgumentNullException(nameof(identity));
             }
@@ -966,7 +961,7 @@ namespace OpenIddict.Abstractions
         /// <returns>The claims identity.</returns>
         public static ClaimsPrincipal RemoveClaims(this ClaimsPrincipal principal, string type)
         {
-            if (principal == null)
+            if (principal is null)
             {
                 throw new ArgumentNullException(nameof(principal));
             }
@@ -996,7 +991,7 @@ namespace OpenIddict.Abstractions
         /// <returns>The claims identity.</returns>
         public static ClaimsIdentity SetClaims(this ClaimsIdentity identity, string type, string? value)
         {
-            if (identity == null)
+            if (identity is null)
             {
                 throw new ArgumentNullException(nameof(identity));
             }
@@ -1025,7 +1020,7 @@ namespace OpenIddict.Abstractions
         /// <returns>The claims identity.</returns>
         public static ClaimsPrincipal SetClaim(this ClaimsPrincipal principal, string type, string? value)
         {
-            if (principal == null)
+            if (principal is null)
             {
                 throw new ArgumentNullException(nameof(principal));
             }
@@ -1054,7 +1049,7 @@ namespace OpenIddict.Abstractions
         /// <returns>The claims identity.</returns>
         public static ClaimsIdentity SetClaims(this ClaimsIdentity identity, string type, ImmutableArray<string> values)
         {
-            if (identity == null)
+            if (identity is null)
             {
                 throw new ArgumentNullException(nameof(identity));
             }
@@ -1083,7 +1078,7 @@ namespace OpenIddict.Abstractions
         /// <returns>The claims identity.</returns>
         public static ClaimsPrincipal SetClaims(this ClaimsPrincipal principal, string type, ImmutableArray<string> values)
         {
-            if (principal == null)
+            if (principal is null)
             {
                 throw new ArgumentNullException(nameof(principal));
             }
@@ -1110,13 +1105,13 @@ namespace OpenIddict.Abstractions
         /// <returns>The creation date or <c>null</c> if the claim cannot be found.</returns>
         public static DateTimeOffset? GetCreationDate(this ClaimsPrincipal principal)
         {
-            if (principal == null)
+            if (principal is null)
             {
                 throw new ArgumentNullException(nameof(principal));
             }
 
             var claim = principal.FindFirst(Claims.Private.CreationDate);
-            if (claim == null)
+            if (claim is null)
             {
                 return null;
             }
@@ -1136,13 +1131,13 @@ namespace OpenIddict.Abstractions
         /// <returns>The expiration date or <c>null</c> if the claim cannot be found.</returns>
         public static DateTimeOffset? GetExpirationDate(this ClaimsPrincipal principal)
         {
-            if (principal == null)
+            if (principal is null)
             {
                 throw new ArgumentNullException(nameof(principal));
             }
 
             var claim = principal.FindFirst(Claims.Private.ExpirationDate);
-            if (claim == null)
+            if (claim is null)
             {
                 return null;
             }
@@ -1275,7 +1270,7 @@ namespace OpenIddict.Abstractions
         /// <returns><c>true</c> if the principal contains the given audience.</returns>
         public static bool HasAudience(this ClaimsPrincipal principal, string audience)
         {
-            if (principal == null)
+            if (principal is null)
             {
                 throw new ArgumentNullException(nameof(principal));
             }
@@ -1304,7 +1299,7 @@ namespace OpenIddict.Abstractions
         /// <returns><c>true</c> if the principal contains the given presenter.</returns>
         public static bool HasPresenter(this ClaimsPrincipal principal, string presenter)
         {
-            if (principal == null)
+            if (principal is null)
             {
                 throw new ArgumentNullException(nameof(principal));
             }
@@ -1333,7 +1328,7 @@ namespace OpenIddict.Abstractions
         /// <returns><c>true</c> if the principal contains the given resource.</returns>
         public static bool HasResource(this ClaimsPrincipal principal, string resource)
         {
-            if (principal == null)
+            if (principal is null)
             {
                 throw new ArgumentNullException(nameof(principal));
             }
@@ -1362,7 +1357,7 @@ namespace OpenIddict.Abstractions
         /// <returns><c>true</c> if the principal contains the given scope.</returns>
         public static bool HasScope(this ClaimsPrincipal principal, string scope)
         {
-            if (principal == null)
+            if (principal is null)
             {
                 throw new ArgumentNullException(nameof(principal));
             }
@@ -1383,7 +1378,7 @@ namespace OpenIddict.Abstractions
         /// <returns><c>true</c> if the token type matches the specified type.</returns>
         public static bool HasTokenType(this ClaimsPrincipal principal, string type)
         {
-            if (principal == null)
+            if (principal is null)
             {
                 throw new ArgumentNullException(nameof(principal));
             }
@@ -1617,7 +1612,7 @@ namespace OpenIddict.Abstractions
 
         private static ImmutableArray<string> GetValues(string? source, char[] separators)
         {
-            Debug.Assert(separators != null && separators.Length != 0, SR.GetResourceString(SR.ID5001));
+            Debug.Assert(separators is not null && separators.Length != 0, SR.GetResourceString(SR.ID5001));
 
             if (string.IsNullOrEmpty(source))
             {
@@ -1648,7 +1643,7 @@ namespace OpenIddict.Abstractions
         private static bool HasValue(string? source, string value, char[] separators)
         {
             Debug.Assert(!string.IsNullOrEmpty(value), SR.GetResourceString(SR.ID5002));
-            Debug.Assert(separators != null && separators.Length != 0, SR.GetResourceString(SR.ID5001));
+            Debug.Assert(separators is not null && separators.Length != 0, SR.GetResourceString(SR.ID5001));
 
             if (string.IsNullOrEmpty(source))
             {
@@ -1674,7 +1669,7 @@ namespace OpenIddict.Abstractions
 
         private static StringSegment TrimStart(StringSegment segment, char[] separators)
         {
-            Debug.Assert(separators != null && separators.Length != 0, SR.GetResourceString(SR.ID5001));
+            Debug.Assert(separators is not null && separators.Length != 0, SR.GetResourceString(SR.ID5001));
 
             var index = segment.Offset;
 
@@ -1693,7 +1688,7 @@ namespace OpenIddict.Abstractions
 
         private static StringSegment TrimEnd(StringSegment segment, char[] separators)
         {
-            Debug.Assert(separators != null && separators.Length != 0, SR.GetResourceString(SR.ID5001));
+            Debug.Assert(separators is not null && separators.Length != 0, SR.GetResourceString(SR.ID5001));
 
             var index = segment.Offset + segment.Length - 1;
 
@@ -1712,14 +1707,14 @@ namespace OpenIddict.Abstractions
 
         private static StringSegment Trim(StringSegment segment, char[] separators)
         {
-            Debug.Assert(separators != null && separators.Length != 0, SR.GetResourceString(SR.ID5001));
+            Debug.Assert(separators is not null && separators.Length != 0, SR.GetResourceString(SR.ID5001));
 
             return TrimEnd(TrimStart(segment, separators), separators);
         }
 
         private static bool IsSeparator(char character, char[] separators)
         {
-            Debug.Assert(separators != null && separators.Length != 0, SR.GetResourceString(SR.ID5001));
+            Debug.Assert(separators is not null && separators.Length != 0, SR.GetResourceString(SR.ID5001));
 
             for (var index = 0; index < separators!.Length; index++)
             {
@@ -1734,7 +1729,7 @@ namespace OpenIddict.Abstractions
 
         private static TimeSpan? GetLifetime(ClaimsPrincipal principal, string type)
         {
-            if (principal == null)
+            if (principal is null)
             {
                 throw new ArgumentNullException(nameof(principal));
             }

src/OpenIddict.Abstractions/Primitives/OpenIddictMessage.cs

@@ -68,7 +68,7 @@ namespace OpenIddict.Abstractions
         /// <param name="parameters">The message parameters.</param>
         public OpenIddictMessage(IEnumerable<KeyValuePair<string, OpenIddictParameter>> parameters)
         {
-            if (parameters == null)
+            if (parameters is null)
             {
                 throw new ArgumentNullException(nameof(parameters));
             }
@@ -85,7 +85,7 @@ namespace OpenIddict.Abstractions
         /// <param name="parameters">The message parameters.</param>
         public OpenIddictMessage(IEnumerable<KeyValuePair<string, string?>> parameters)
         {
-            if (parameters == null)
+            if (parameters is null)
             {
                 throw new ArgumentNullException(nameof(parameters));
             }
@@ -113,7 +113,7 @@ namespace OpenIddict.Abstractions
         /// <param name="parameters">The message parameters.</param>
         public OpenIddictMessage(IEnumerable<KeyValuePair<string, string?[]?>> parameters)
         {
-            if (parameters == null)
+            if (parameters is null)
             {
                 throw new ArgumentNullException(nameof(parameters));
             }
@@ -140,7 +140,7 @@ namespace OpenIddict.Abstractions
         /// <param name="parameters">The message parameters.</param>
         public OpenIddictMessage(IEnumerable<KeyValuePair<string, StringValues>> parameters)
         {
-            if (parameters == null)
+            if (parameters is null)
             {
                 throw new ArgumentNullException(nameof(parameters));
             }
@@ -279,7 +279,7 @@ namespace OpenIddict.Abstractions
             }
 
             // If the parameter value is null or empty, remove the corresponding entry from the collection.
-            if (value == null || OpenIddictParameter.IsNullOrEmpty(value.GetValueOrDefault()))
+            if (value is null || OpenIddictParameter.IsNullOrEmpty(value.GetValueOrDefault()))
             {
                 Parameters.Remove(name);
             }
@@ -360,7 +360,7 @@ namespace OpenIddict.Abstractions
         /// <param name="writer">The UTF-8 JSON writer.</param>
         public void WriteTo(Utf8JsonWriter writer)
         {
-            if (writer == null)
+            if (writer is null)
             {
                 throw new ArgumentNullException(nameof(writer));
             }

src/OpenIddict.Abstractions/Primitives/OpenIddictParameter.cs

@@ -505,7 +505,7 @@ namespace OpenIddict.Abstractions
         /// <param name="writer">The UTF-8 JSON writer.</param>
         public void WriteTo(Utf8JsonWriter writer)
         {
-            if (writer == null)
+            if (writer is null)
             {
                 throw new ArgumentNullException(nameof(writer));
             }

src/OpenIddict.Core/Caches/OpenIddictApplicationCache.cs

@@ -45,7 +45,7 @@ namespace OpenIddict.Core
         /// <inheritdoc/>
         public async ValueTask AddAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -127,7 +127,7 @@ namespace OpenIddict.Core
 
             async Task<TApplication?> ExecuteAsync()
             {
-                if ((application = await _store.FindByClientIdAsync(identifier, cancellationToken)) != null)
+                if ((application = await _store.FindByClientIdAsync(identifier, cancellationToken)) is not null)
                 {
                     await AddAsync(application, cancellationToken);
                 }
@@ -161,7 +161,7 @@ namespace OpenIddict.Core
 
             async Task<TApplication?> ExecuteAsync()
             {
-                if ((application = await _store.FindByIdAsync(identifier, cancellationToken)) != null)
+                if ((application = await _store.FindByIdAsync(identifier, cancellationToken)) is not null)
                 {
                     await AddAsync(application, cancellationToken);
                 }
@@ -257,7 +257,7 @@ namespace OpenIddict.Core
         /// <inheritdoc/>
         public async ValueTask RemoveAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -284,17 +284,17 @@ namespace OpenIddict.Core
         /// <returns>A <see cref="ValueTask"/> that can be used to monitor the asynchronous operation.</returns>
         protected virtual async ValueTask CreateEntryAsync(object key, TApplication? application, CancellationToken cancellationToken)
         {
-            if (key == null)
+            if (key is null)
             {
                 throw new ArgumentNullException(nameof(key));
             }
 
             using var entry = _cache.CreateEntry(key);
 
-            if (application != null)
+            if (application is not null)
             {
                 var signal = await CreateExpirationSignalAsync(application, cancellationToken);
-                if (signal == null)
+                if (signal is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1196));
                 }
@@ -316,7 +316,7 @@ namespace OpenIddict.Core
         protected virtual async ValueTask CreateEntryAsync(
             object key, ImmutableArray<TApplication> applications, CancellationToken cancellationToken)
         {
-            if (key == null)
+            if (key is null)
             {
                 throw new ArgumentNullException(nameof(key));
             }
@@ -326,7 +326,7 @@ namespace OpenIddict.Core
             foreach (var application in applications)
             {
                 var signal = await CreateExpirationSignalAsync(application, cancellationToken);
-                if (signal == null)
+                if (signal is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1196));
                 }
@@ -351,7 +351,7 @@ namespace OpenIddict.Core
         protected virtual async ValueTask<IChangeToken> CreateExpirationSignalAsync(
             TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }

src/OpenIddict.Core/Caches/OpenIddictAuthorizationCache.cs

@@ -45,7 +45,7 @@ namespace OpenIddict.Core
         /// <inheritdoc/>
         public async ValueTask AddAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -378,7 +378,7 @@ namespace OpenIddict.Core
 
             async Task<TAuthorization?> ExecuteAsync()
             {
-                if ((authorization = await _store.FindByIdAsync(identifier, cancellationToken)) != null)
+                if ((authorization = await _store.FindByIdAsync(identifier, cancellationToken)) is not null)
                 {
                     await AddAsync(authorization, cancellationToken);
                 }
@@ -433,7 +433,7 @@ namespace OpenIddict.Core
         /// <inheritdoc/>
         public async ValueTask RemoveAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -460,17 +460,17 @@ namespace OpenIddict.Core
         /// <returns>A <see cref="ValueTask"/> that can be used to monitor the asynchronous operation.</returns>
         protected virtual async ValueTask CreateEntryAsync(object key, TAuthorization? authorization, CancellationToken cancellationToken)
         {
-            if (key == null)
+            if (key is null)
             {
                 throw new ArgumentNullException(nameof(key));
             }
 
             using var entry = _cache.CreateEntry(key);
 
-            if (authorization != null)
+            if (authorization is not null)
             {
                 var signal = await CreateExpirationSignalAsync(authorization, cancellationToken);
-                if (signal == null)
+                if (signal is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1196));
                 }
@@ -492,7 +492,7 @@ namespace OpenIddict.Core
         protected virtual async ValueTask CreateEntryAsync(
             object key, ImmutableArray<TAuthorization> authorizations, CancellationToken cancellationToken)
         {
-            if (key == null)
+            if (key is null)
             {
                 throw new ArgumentNullException(nameof(key));
             }
@@ -502,7 +502,7 @@ namespace OpenIddict.Core
             foreach (var authorization in authorizations)
             {
                 var signal = await CreateExpirationSignalAsync(authorization, cancellationToken);
-                if (signal == null)
+                if (signal is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1196));
                 }
@@ -527,7 +527,7 @@ namespace OpenIddict.Core
         protected virtual async ValueTask<IChangeToken> CreateExpirationSignalAsync(
             TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }

src/OpenIddict.Core/Caches/OpenIddictScopeCache.cs

@@ -46,7 +46,7 @@ namespace OpenIddict.Core
         /// <inheritdoc/>
         public async ValueTask AddAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -119,7 +119,7 @@ namespace OpenIddict.Core
 
             async Task<TScope?> ExecuteAsync()
             {
-                if ((scope = await _store.FindByIdAsync(identifier, cancellationToken)) != null)
+                if ((scope = await _store.FindByIdAsync(identifier, cancellationToken)) is not null)
                 {
                     await AddAsync(scope, cancellationToken);
                 }
@@ -151,7 +151,7 @@ namespace OpenIddict.Core
 
             async Task<TScope?> ExecuteAsync()
             {
-                if ((scope = await _store.FindByNameAsync(name, cancellationToken)) != null)
+                if ((scope = await _store.FindByNameAsync(name, cancellationToken)) is not null)
                 {
                     await AddAsync(scope, cancellationToken);
                 }
@@ -231,7 +231,7 @@ namespace OpenIddict.Core
         /// <inheritdoc/>
         public async ValueTask RemoveAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -258,17 +258,17 @@ namespace OpenIddict.Core
         /// <returns>A <see cref="ValueTask"/> that can be used to monitor the asynchronous operation.</returns>
         protected virtual async ValueTask CreateEntryAsync(object key, TScope? scope, CancellationToken cancellationToken)
         {
-            if (key == null)
+            if (key is null)
             {
                 throw new ArgumentNullException(nameof(key));
             }
 
             using var entry = _cache.CreateEntry(key);
 
-            if (scope != null)
+            if (scope is not null)
             {
                 var signal = await CreateExpirationSignalAsync(scope, cancellationToken);
-                if (signal == null)
+                if (signal is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1196));
                 }
@@ -290,7 +290,7 @@ namespace OpenIddict.Core
         protected virtual async ValueTask CreateEntryAsync(
             object key, ImmutableArray<TScope> scopes, CancellationToken cancellationToken)
         {
-            if (key == null)
+            if (key is null)
             {
                 throw new ArgumentNullException(nameof(key));
             }
@@ -300,7 +300,7 @@ namespace OpenIddict.Core
             foreach (var scope in scopes)
             {
                 var signal = await CreateExpirationSignalAsync(scope, cancellationToken);
-                if (signal == null)
+                if (signal is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1196));
                 }
@@ -324,7 +324,7 @@ namespace OpenIddict.Core
         /// </returns>
         protected virtual async ValueTask<IChangeToken> CreateExpirationSignalAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }

src/OpenIddict.Core/Caches/OpenIddictTokenCache.cs

@@ -45,7 +45,7 @@ namespace OpenIddict.Core
         /// <inheritdoc/>
         public async ValueTask AddAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -396,7 +396,7 @@ namespace OpenIddict.Core
 
             async Task<TToken?> ExecuteAsync()
             {
-                if ((token = await _store.FindByIdAsync(identifier, cancellationToken)) != null)
+                if ((token = await _store.FindByIdAsync(identifier, cancellationToken)) is not null)
                 {
                     await AddAsync(token, cancellationToken);
                 }
@@ -430,7 +430,7 @@ namespace OpenIddict.Core
 
             async Task<TToken?> ExecuteAsync()
             {
-                if ((token = await _store.FindByReferenceIdAsync(identifier, cancellationToken)) != null)
+                if ((token = await _store.FindByReferenceIdAsync(identifier, cancellationToken)) is not null)
                 {
                     await AddAsync(token, cancellationToken);
                 }
@@ -485,7 +485,7 @@ namespace OpenIddict.Core
         /// <inheritdoc/>
         public async ValueTask RemoveAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -512,17 +512,17 @@ namespace OpenIddict.Core
         /// <returns>A <see cref="ValueTask"/> that can be used to monitor the asynchronous operation.</returns>
         protected virtual async ValueTask CreateEntryAsync(object key, TToken? token, CancellationToken cancellationToken)
         {
-            if (key == null)
+            if (key is null)
             {
                 throw new ArgumentNullException(nameof(key));
             }
 
             using var entry = _cache.CreateEntry(key);
 
-            if (token != null)
+            if (token is not null)
             {
                 var signal = await CreateExpirationSignalAsync(token, cancellationToken);
-                if (signal == null)
+                if (signal is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1196));
                 }
@@ -544,7 +544,7 @@ namespace OpenIddict.Core
         protected virtual async ValueTask CreateEntryAsync(
             object key, ImmutableArray<TToken> tokens, CancellationToken cancellationToken)
         {
-            if (key == null)
+            if (key is null)
             {
                 throw new ArgumentNullException(nameof(key));
             }
@@ -554,7 +554,7 @@ namespace OpenIddict.Core
             foreach (var token in tokens)
             {
                 var signal = await CreateExpirationSignalAsync(token, cancellationToken);
-                if (signal == null)
+                if (signal is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1196));
                 }
@@ -578,7 +578,7 @@ namespace OpenIddict.Core
         /// </returns>
         protected virtual async ValueTask<IChangeToken> CreateExpirationSignalAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }

src/OpenIddict.Core/Managers/OpenIddictApplicationManager.cs

@@ -111,7 +111,7 @@ namespace OpenIddict.Core
         public virtual ValueTask<long> CountAsync<TResult>(
             Func<IQueryable<TApplication>, IQueryable<TResult>> query, CancellationToken cancellationToken = default)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -143,7 +143,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual async ValueTask CreateAsync(TApplication application, string? secret, CancellationToken cancellationToken = default)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -218,13 +218,13 @@ namespace OpenIddict.Core
         public virtual async ValueTask<TApplication> CreateAsync(
             OpenIddictApplicationDescriptor descriptor, CancellationToken cancellationToken = default)
         {
-            if (descriptor == null)
+            if (descriptor is null)
             {
                 throw new ArgumentNullException(nameof(descriptor));
             }
 
             var application = await Store.InstantiateAsync(cancellationToken);
-            if (application == null)
+            if (application is null)
             {
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID1207));
             }
@@ -255,7 +255,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual async ValueTask DeleteAsync(TApplication application, CancellationToken cancellationToken = default)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -289,7 +289,7 @@ namespace OpenIddict.Core
                 await Store.FindByClientIdAsync(identifier, cancellationToken) :
                 await Cache.FindByClientIdAsync(identifier, cancellationToken);
 
-            if (application == null)
+            if (application is null)
             {
                 return null;
             }
@@ -326,7 +326,7 @@ namespace OpenIddict.Core
                 await Store.FindByIdAsync(identifier, cancellationToken) :
                 await Cache.FindByIdAsync(identifier, cancellationToken);
 
-            if (application == null)
+            if (application is null)
             {
                 return null;
             }
@@ -440,7 +440,7 @@ namespace OpenIddict.Core
         public virtual ValueTask<TResult> GetAsync<TResult>(
             Func<IQueryable<TApplication>, IQueryable<TResult>> query, CancellationToken cancellationToken = default)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -464,7 +464,7 @@ namespace OpenIddict.Core
             Func<IQueryable<TApplication>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken = default)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -484,7 +484,7 @@ namespace OpenIddict.Core
         public virtual ValueTask<string?> GetClientIdAsync(
             TApplication application, CancellationToken cancellationToken = default)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -504,7 +504,7 @@ namespace OpenIddict.Core
         public virtual ValueTask<string?> GetClientTypeAsync(
             TApplication application, CancellationToken cancellationToken = default)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -524,7 +524,7 @@ namespace OpenIddict.Core
         public virtual async ValueTask<string?> GetConsentTypeAsync(
             TApplication application, CancellationToken cancellationToken = default)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -550,7 +550,7 @@ namespace OpenIddict.Core
         public virtual ValueTask<string?> GetDisplayNameAsync(
             TApplication application, CancellationToken cancellationToken = default)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -570,13 +570,13 @@ namespace OpenIddict.Core
         public virtual async ValueTask<ImmutableDictionary<CultureInfo, string>> GetDisplayNamesAsync(
             TApplication application, CancellationToken cancellationToken = default)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
 
             var names = await Store.GetDisplayNamesAsync(application, cancellationToken);
-            if (names == null || names.Count == 0)
+            if (names is null || names.Count == 0)
             {
                 return ImmutableDictionary.Create<CultureInfo, string>();
             }
@@ -595,7 +595,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual ValueTask<string?> GetIdAsync(TApplication application, CancellationToken cancellationToken = default)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -633,18 +633,18 @@ namespace OpenIddict.Core
         public virtual async ValueTask<string?> GetLocalizedDisplayNameAsync(
             TApplication application, CultureInfo culture, CancellationToken cancellationToken = default)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
 
-            if (culture == null)
+            if (culture is null)
             {
                 throw new ArgumentNullException(nameof(culture));
             }
 
             var names = await Store.GetDisplayNamesAsync(application, cancellationToken);
-            if (names == null || names.IsEmpty)
+            if (names is null || names.IsEmpty)
             {
                 return await Store.GetDisplayNameAsync(application, cancellationToken);
             }
@@ -676,7 +676,7 @@ namespace OpenIddict.Core
         public virtual ValueTask<ImmutableArray<string>> GetPermissionsAsync(
             TApplication application, CancellationToken cancellationToken = default)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -696,7 +696,7 @@ namespace OpenIddict.Core
         public virtual ValueTask<ImmutableArray<string>> GetPostLogoutRedirectUrisAsync(
             TApplication application, CancellationToken cancellationToken = default)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -716,7 +716,7 @@ namespace OpenIddict.Core
         public virtual ValueTask<ImmutableArray<string>> GetRedirectUrisAsync(
             TApplication application, CancellationToken cancellationToken = default)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -736,7 +736,7 @@ namespace OpenIddict.Core
         public virtual ValueTask<ImmutableArray<string>> GetRequirementsAsync(
             TApplication application, CancellationToken cancellationToken = default)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -754,7 +754,7 @@ namespace OpenIddict.Core
         public virtual async ValueTask<bool> HasClientTypeAsync(
             TApplication application, string type, CancellationToken cancellationToken = default)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -777,7 +777,7 @@ namespace OpenIddict.Core
         public virtual async ValueTask<bool> HasConsentTypeAsync(
             TApplication application, string type, CancellationToken cancellationToken = default)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -800,7 +800,7 @@ namespace OpenIddict.Core
         public virtual async ValueTask<bool> HasPermissionAsync(
             TApplication application, string permission, CancellationToken cancellationToken = default)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -823,7 +823,7 @@ namespace OpenIddict.Core
         public virtual async ValueTask<bool> HasRequirementAsync(
             TApplication application, string requirement, CancellationToken cancellationToken = default)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -857,7 +857,7 @@ namespace OpenIddict.Core
         public virtual IAsyncEnumerable<TResult> ListAsync<TResult>(
             Func<IQueryable<TApplication>, IQueryable<TResult>> query, CancellationToken cancellationToken = default)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -878,7 +878,7 @@ namespace OpenIddict.Core
             Func<IQueryable<TApplication>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken = default)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -898,12 +898,12 @@ namespace OpenIddict.Core
         public virtual async ValueTask PopulateAsync(TApplication application,
             OpenIddictApplicationDescriptor descriptor, CancellationToken cancellationToken = default)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
 
-            if (descriptor == null)
+            if (descriptor is null)
             {
                 throw new ArgumentNullException(nameof(descriptor));
             }
@@ -935,12 +935,12 @@ namespace OpenIddict.Core
             OpenIddictApplicationDescriptor descriptor,
             TApplication application, CancellationToken cancellationToken = default)
         {
-            if (descriptor == null)
+            if (descriptor is null)
             {
                 throw new ArgumentNullException(nameof(descriptor));
             }
 
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -1008,7 +1008,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual async ValueTask UpdateAsync(TApplication application, CancellationToken cancellationToken = default)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -1063,7 +1063,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual async ValueTask UpdateAsync(TApplication application, string? secret, CancellationToken cancellationToken = default)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -1094,12 +1094,12 @@ namespace OpenIddict.Core
         public virtual async ValueTask UpdateAsync(TApplication application,
             OpenIddictApplicationDescriptor descriptor, CancellationToken cancellationToken = default)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
 
-            if (descriptor == null)
+            if (descriptor is null)
             {
                 throw new ArgumentNullException(nameof(descriptor));
             }
@@ -1129,7 +1129,7 @@ namespace OpenIddict.Core
         public virtual async IAsyncEnumerable<ValidationResult> ValidateAsync(
             TApplication application, [EnumeratorCancellation] CancellationToken cancellationToken = default)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -1148,7 +1148,7 @@ namespace OpenIddict.Core
                 // the casing is different). To avoid issues when the client identifier is part of an index
                 // using the same collation, an error is added even if the two identifiers don't exactly match.
                 var other = await Store.FindByClientIdAsync(identifier, cancellationToken);
-                if (other != null && !string.Equals(
+                if (other is not null && !string.Equals(
                     await Store.GetIdAsync(other, cancellationToken),
                     await Store.GetIdAsync(application, cancellationToken), StringComparison.Ordinal))
                 {
@@ -1232,7 +1232,7 @@ namespace OpenIddict.Core
         public virtual async ValueTask<bool> ValidateClientSecretAsync(
             TApplication application, string secret, CancellationToken cancellationToken = default)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -1279,7 +1279,7 @@ namespace OpenIddict.Core
         public virtual async ValueTask<bool> ValidateRedirectUriAsync(
             TApplication application, string address, CancellationToken cancellationToken = default)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }

src/OpenIddict.Core/Managers/OpenIddictAuthorizationManager.cs

@@ -98,7 +98,7 @@ namespace OpenIddict.Core
         public virtual ValueTask<long> CountAsync<TResult>(
             Func<IQueryable<TAuthorization>, IQueryable<TResult>> query, CancellationToken cancellationToken = default)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -116,7 +116,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual async ValueTask CreateAsync(TAuthorization authorization, CancellationToken cancellationToken = default)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -174,13 +174,13 @@ namespace OpenIddict.Core
         public virtual async ValueTask<TAuthorization> CreateAsync(
             OpenIddictAuthorizationDescriptor descriptor, CancellationToken cancellationToken = default)
         {
-            if (descriptor == null)
+            if (descriptor is null)
             {
                 throw new ArgumentNullException(nameof(descriptor));
             }
 
             var authorization = await Store.InstantiateAsync(cancellationToken);
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID1219));
             }
@@ -207,7 +207,7 @@ namespace OpenIddict.Core
             ClaimsPrincipal principal, string subject, string client,
             string type, ImmutableArray<string> scopes, CancellationToken cancellationToken = default)
         {
-            if (principal == null)
+            if (principal is null)
             {
                 throw new ArgumentNullException(nameof(principal));
             }
@@ -251,7 +251,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual async ValueTask DeleteAsync(TAuthorization authorization, CancellationToken cancellationToken = default)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -560,7 +560,7 @@ namespace OpenIddict.Core
                 await Store.FindByIdAsync(identifier, cancellationToken) :
                 await Cache.FindByIdAsync(identifier, cancellationToken);
 
-            if (authorization == null)
+            if (authorization is null)
             {
                 return null;
             }
@@ -630,7 +630,7 @@ namespace OpenIddict.Core
         public virtual ValueTask<string?> GetApplicationIdAsync(
             TAuthorization authorization, CancellationToken cancellationToken = default)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -651,7 +651,7 @@ namespace OpenIddict.Core
         public virtual ValueTask<TResult> GetAsync<TResult>(
             Func<IQueryable<TAuthorization>, IQueryable<TResult>> query, CancellationToken cancellationToken = default)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -675,7 +675,7 @@ namespace OpenIddict.Core
             Func<IQueryable<TAuthorization>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken = default)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -695,7 +695,7 @@ namespace OpenIddict.Core
         public virtual ValueTask<DateTimeOffset?> GetCreationDateAsync(
             TAuthorization authorization, CancellationToken cancellationToken = default)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -714,7 +714,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual ValueTask<string?> GetIdAsync(TAuthorization authorization, CancellationToken cancellationToken = default)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -734,7 +734,7 @@ namespace OpenIddict.Core
         public virtual ValueTask<ImmutableArray<string>> GetScopesAsync(
             TAuthorization authorization, CancellationToken cancellationToken = default)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -754,7 +754,7 @@ namespace OpenIddict.Core
         public virtual ValueTask<string?> GetStatusAsync(
             TAuthorization authorization, CancellationToken cancellationToken = default)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -774,7 +774,7 @@ namespace OpenIddict.Core
         public virtual ValueTask<string?> GetSubjectAsync(
             TAuthorization authorization, CancellationToken cancellationToken = default)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -794,7 +794,7 @@ namespace OpenIddict.Core
         public virtual ValueTask<string?> GetTypeAsync(
             TAuthorization authorization, CancellationToken cancellationToken = default)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -812,7 +812,7 @@ namespace OpenIddict.Core
         public virtual async ValueTask<bool> HasScopesAsync(TAuthorization authorization,
             ImmutableArray<string> scopes, CancellationToken cancellationToken = default)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -831,7 +831,7 @@ namespace OpenIddict.Core
         public virtual async ValueTask<bool> HasStatusAsync(TAuthorization authorization,
             string status, CancellationToken cancellationToken = default)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -854,7 +854,7 @@ namespace OpenIddict.Core
         public virtual async ValueTask<bool> HasTypeAsync(
             TAuthorization authorization, string type, CancellationToken cancellationToken = default)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -888,7 +888,7 @@ namespace OpenIddict.Core
         public virtual IAsyncEnumerable<TResult> ListAsync<TResult>(
             Func<IQueryable<TAuthorization>, IQueryable<TResult>> query, CancellationToken cancellationToken = default)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -909,7 +909,7 @@ namespace OpenIddict.Core
             Func<IQueryable<TAuthorization>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken = default)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -929,12 +929,12 @@ namespace OpenIddict.Core
         public virtual async ValueTask PopulateAsync(TAuthorization authorization,
             OpenIddictAuthorizationDescriptor descriptor, CancellationToken cancellationToken = default)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
 
-            if (descriptor == null)
+            if (descriptor is null)
             {
                 throw new ArgumentNullException(nameof(descriptor));
             }
@@ -960,12 +960,12 @@ namespace OpenIddict.Core
             OpenIddictAuthorizationDescriptor descriptor,
             TAuthorization authorization, CancellationToken cancellationToken = default)
         {
-            if (descriptor == null)
+            if (descriptor is null)
             {
                 throw new ArgumentNullException(nameof(descriptor));
             }
 
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -1007,7 +1007,7 @@ namespace OpenIddict.Core
         public virtual async ValueTask SetApplicationIdAsync(
             TAuthorization authorization, string? identifier, CancellationToken cancellationToken = default)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -1024,7 +1024,7 @@ namespace OpenIddict.Core
         /// <returns><c>true</c> if the authorization was successfully revoked, <c>false</c> otherwise.</returns>
         public virtual async ValueTask<bool> TryRevokeAsync(TAuthorization authorization, CancellationToken cancellationToken = default)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -1071,7 +1071,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual async ValueTask UpdateAsync(TAuthorization authorization, CancellationToken cancellationToken = default)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -1125,12 +1125,12 @@ namespace OpenIddict.Core
         public virtual async ValueTask UpdateAsync(TAuthorization authorization,
             OpenIddictAuthorizationDescriptor descriptor, CancellationToken cancellationToken = default)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
 
-            if (descriptor == null)
+            if (descriptor is null)
             {
                 throw new ArgumentNullException(nameof(descriptor));
             }
@@ -1148,7 +1148,7 @@ namespace OpenIddict.Core
         public virtual async IAsyncEnumerable<ValidationResult> ValidateAsync(
             TAuthorization authorization, [EnumeratorCancellation] CancellationToken cancellationToken = default)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }

src/OpenIddict.Core/Managers/OpenIddictScopeManager.cs

@@ -97,7 +97,7 @@ namespace OpenIddict.Core
         public virtual ValueTask<long> CountAsync<TResult>(
             Func<IQueryable<TScope>, IQueryable<TResult>> query, CancellationToken cancellationToken = default)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -115,7 +115,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual async ValueTask CreateAsync(TScope scope, CancellationToken cancellationToken = default)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -167,13 +167,13 @@ namespace OpenIddict.Core
         public virtual async ValueTask<TScope> CreateAsync(
             OpenIddictScopeDescriptor descriptor, CancellationToken cancellationToken = default)
         {
-            if (descriptor == null)
+            if (descriptor is null)
             {
                 throw new ArgumentNullException(nameof(descriptor));
             }
 
             var scope = await Store.InstantiateAsync(cancellationToken);
-            if (scope == null)
+            if (scope is null)
             {
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID1222));
             }
@@ -194,7 +194,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual async ValueTask DeleteAsync(TScope scope, CancellationToken cancellationToken = default)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -227,7 +227,7 @@ namespace OpenIddict.Core
                 await Store.FindByIdAsync(identifier, cancellationToken) :
                 await Cache.FindByIdAsync(identifier, cancellationToken);
 
-            if (scope == null)
+            if (scope is null)
             {
                 return null;
             }
@@ -264,7 +264,7 @@ namespace OpenIddict.Core
                 await Store.FindByNameAsync(name, cancellationToken) :
                 await Cache.FindByNameAsync(name, cancellationToken);
 
-            if (scope == null)
+            if (scope is null)
             {
                 return null;
             }
@@ -378,7 +378,7 @@ namespace OpenIddict.Core
         public virtual ValueTask<TResult> GetAsync<TResult>(
             Func<IQueryable<TScope>, IQueryable<TResult>> query, CancellationToken cancellationToken = default)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -402,7 +402,7 @@ namespace OpenIddict.Core
             Func<IQueryable<TScope>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken = default)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -421,7 +421,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual ValueTask<string?> GetDescriptionAsync(TScope scope, CancellationToken cancellationToken = default)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -441,13 +441,13 @@ namespace OpenIddict.Core
         public virtual async ValueTask<ImmutableDictionary<CultureInfo, string>> GetDescriptionsAsync(
             TScope scope, CancellationToken cancellationToken = default)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
 
             var descriptions = await Store.GetDescriptionsAsync(scope, cancellationToken);
-            if (descriptions == null || descriptions.Count == 0)
+            if (descriptions is null || descriptions.Count == 0)
             {
                 return ImmutableDictionary.Create<CultureInfo, string>();
             }
@@ -466,7 +466,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual ValueTask<string?> GetDisplayNameAsync(TScope scope, CancellationToken cancellationToken = default)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -486,13 +486,13 @@ namespace OpenIddict.Core
         public virtual async ValueTask<ImmutableDictionary<CultureInfo, string>> GetDisplayNamesAsync(
             TScope scope, CancellationToken cancellationToken = default)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
 
             var names = await Store.GetDisplayNamesAsync(scope, cancellationToken);
-            if (names == null || names.Count == 0)
+            if (names is null || names.Count == 0)
             {
                 return ImmutableDictionary.Create<CultureInfo, string>();
             }
@@ -511,7 +511,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual ValueTask<string?> GetIdAsync(TScope scope, CancellationToken cancellationToken = default)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -548,18 +548,18 @@ namespace OpenIddict.Core
         public virtual async ValueTask<string?> GetLocalizedDisplayNameAsync(
             TScope scope, CultureInfo culture, CancellationToken cancellationToken = default)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
 
-            if (culture == null)
+            if (culture is null)
             {
                 throw new ArgumentNullException(nameof(culture));
             }
 
             var names = await Store.GetDisplayNamesAsync(scope, cancellationToken);
-            if (names == null || names.IsEmpty)
+            if (names is null || names.IsEmpty)
             {
                 return await Store.GetDisplayNameAsync(scope, cancellationToken);
             }
@@ -608,18 +608,18 @@ namespace OpenIddict.Core
         public virtual async ValueTask<string?> GetLocalizedDescriptionAsync(
             TScope scope, CultureInfo culture, CancellationToken cancellationToken = default)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
 
-            if (culture == null)
+            if (culture is null)
             {
                 throw new ArgumentNullException(nameof(culture));
             }
 
             var descriptions = await Store.GetDescriptionsAsync(scope, cancellationToken);
-            if (descriptions == null || descriptions.IsEmpty)
+            if (descriptions is null || descriptions.IsEmpty)
             {
                 return await Store.GetDescriptionAsync(scope, cancellationToken);
             }
@@ -650,7 +650,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual ValueTask<string?> GetNameAsync(TScope scope, CancellationToken cancellationToken = default)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -670,7 +670,7 @@ namespace OpenIddict.Core
         public virtual ValueTask<ImmutableArray<string>> GetResourcesAsync(
             TScope scope, CancellationToken cancellationToken = default)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -699,7 +699,7 @@ namespace OpenIddict.Core
         public virtual IAsyncEnumerable<TResult> ListAsync<TResult>(
             Func<IQueryable<TScope>, IQueryable<TResult>> query, CancellationToken cancellationToken = default)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -720,7 +720,7 @@ namespace OpenIddict.Core
             Func<IQueryable<TScope>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken = default)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -762,12 +762,12 @@ namespace OpenIddict.Core
         public virtual async ValueTask PopulateAsync(TScope scope,
             OpenIddictScopeDescriptor descriptor, CancellationToken cancellationToken = default)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
 
-            if (descriptor == null)
+            if (descriptor is null)
             {
                 throw new ArgumentNullException(nameof(descriptor));
             }
@@ -793,12 +793,12 @@ namespace OpenIddict.Core
             OpenIddictScopeDescriptor descriptor,
             TScope scope, CancellationToken cancellationToken = default)
         {
-            if (descriptor == null)
+            if (descriptor is null)
             {
                 throw new ArgumentNullException(nameof(descriptor));
             }
 
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -832,7 +832,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual async ValueTask UpdateAsync(TScope scope, CancellationToken cancellationToken = default)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -886,12 +886,12 @@ namespace OpenIddict.Core
         public virtual async ValueTask UpdateAsync(TScope scope,
             OpenIddictScopeDescriptor descriptor, CancellationToken cancellationToken = default)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
 
-            if (descriptor == null)
+            if (descriptor is null)
             {
                 throw new ArgumentNullException(nameof(descriptor));
             }
@@ -909,7 +909,7 @@ namespace OpenIddict.Core
         public virtual async IAsyncEnumerable<ValidationResult> ValidateAsync(
             TScope scope, [EnumeratorCancellation] CancellationToken cancellationToken = default)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -934,7 +934,7 @@ namespace OpenIddict.Core
                 // the casing is different). To avoid issues when the scope name is part of an index
                 // using the same collation, an error is added even if the two names don't exactly match.
                 var other = await Store.FindByNameAsync(name, cancellationToken);
-                if (other != null && !string.Equals(
+                if (other is not null && !string.Equals(
                     await Store.GetIdAsync(other, cancellationToken),
                     await Store.GetIdAsync(scope, cancellationToken), StringComparison.Ordinal))
                 {

src/OpenIddict.Core/Managers/OpenIddictTokenManager.cs

@@ -98,7 +98,7 @@ namespace OpenIddict.Core
         public virtual ValueTask<long> CountAsync<TResult>(
             Func<IQueryable<TToken>, IQueryable<TResult>> query, CancellationToken cancellationToken = default)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -116,7 +116,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual async ValueTask CreateAsync(TToken token, CancellationToken cancellationToken = default)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -182,13 +182,13 @@ namespace OpenIddict.Core
         public virtual async ValueTask<TToken> CreateAsync(
             OpenIddictTokenDescriptor descriptor, CancellationToken cancellationToken = default)
         {
-            if (descriptor == null)
+            if (descriptor is null)
             {
                 throw new ArgumentNullException(nameof(descriptor));
             }
 
             var token = await Store.InstantiateAsync(cancellationToken);
-            if (token == null)
+            if (token is null)
             {
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID1225));
             }
@@ -209,7 +209,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual async ValueTask DeleteAsync(TToken token, CancellationToken cancellationToken = default)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -486,7 +486,7 @@ namespace OpenIddict.Core
                 await Store.FindByIdAsync(identifier, cancellationToken) :
                 await Cache.FindByIdAsync(identifier, cancellationToken);
 
-            if (token == null)
+            if (token is null)
             {
                 return null;
             }
@@ -526,7 +526,7 @@ namespace OpenIddict.Core
                 await Store.FindByReferenceIdAsync(identifier, cancellationToken) :
                 await Cache.FindByReferenceIdAsync(identifier, cancellationToken);
 
-            if (token == null)
+            if (token is null)
             {
                 return null;
             }
@@ -596,7 +596,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual ValueTask<string?> GetApplicationIdAsync(TToken token, CancellationToken cancellationToken = default)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -617,7 +617,7 @@ namespace OpenIddict.Core
         public virtual ValueTask<TResult> GetAsync<TResult>(
             Func<IQueryable<TToken>, IQueryable<TResult>> query, CancellationToken cancellationToken = default)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -641,7 +641,7 @@ namespace OpenIddict.Core
             Func<IQueryable<TToken>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken = default)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -660,7 +660,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual ValueTask<string?> GetAuthorizationIdAsync(TToken token, CancellationToken cancellationToken = default)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -679,7 +679,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual ValueTask<DateTimeOffset?> GetCreationDateAsync(TToken token, CancellationToken cancellationToken = default)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -698,7 +698,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual ValueTask<DateTimeOffset?> GetExpirationDateAsync(TToken token, CancellationToken cancellationToken = default)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -717,7 +717,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual ValueTask<string?> GetIdAsync(TToken token, CancellationToken cancellationToken = default)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -736,7 +736,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual ValueTask<string?> GetPayloadAsync(TToken token, CancellationToken cancellationToken = default)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -757,7 +757,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual ValueTask<string?> GetReferenceIdAsync(TToken token, CancellationToken cancellationToken = default)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -776,7 +776,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual ValueTask<string?> GetStatusAsync(TToken token, CancellationToken cancellationToken = default)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -795,7 +795,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual ValueTask<string?> GetSubjectAsync(TToken token, CancellationToken cancellationToken = default)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -814,7 +814,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual ValueTask<string?> GetTypeAsync(TToken token, CancellationToken cancellationToken = default)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -831,7 +831,7 @@ namespace OpenIddict.Core
         /// <returns><c>true</c> if the token has the specified status, <c>false</c> otherwise.</returns>
         public virtual async ValueTask<bool> HasStatusAsync(TToken token, string status, CancellationToken cancellationToken = default)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -853,7 +853,7 @@ namespace OpenIddict.Core
         /// <returns><c>true</c> if the token has the specified type, <c>false</c> otherwise.</returns>
         public virtual async ValueTask<bool> HasTypeAsync(TToken token, string type, CancellationToken cancellationToken = default)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -887,7 +887,7 @@ namespace OpenIddict.Core
         public virtual IAsyncEnumerable<TResult> ListAsync<TResult>(
             Func<IQueryable<TToken>, IQueryable<TResult>> query, CancellationToken cancellationToken = default)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -908,7 +908,7 @@ namespace OpenIddict.Core
             Func<IQueryable<TToken>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken = default)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -928,12 +928,12 @@ namespace OpenIddict.Core
         public virtual async ValueTask PopulateAsync(TToken token,
             OpenIddictTokenDescriptor descriptor, CancellationToken cancellationToken = default)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
 
-            if (descriptor == null)
+            if (descriptor is null)
             {
                 throw new ArgumentNullException(nameof(descriptor));
             }
@@ -962,12 +962,12 @@ namespace OpenIddict.Core
             OpenIddictTokenDescriptor descriptor,
             TToken token, CancellationToken cancellationToken = default)
         {
-            if (descriptor == null)
+            if (descriptor is null)
             {
                 throw new ArgumentNullException(nameof(descriptor));
             }
 
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -1007,7 +1007,7 @@ namespace OpenIddict.Core
         public virtual async ValueTask SetApplicationIdAsync(TToken token,
             string? identifier, CancellationToken cancellationToken = default)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -1028,7 +1028,7 @@ namespace OpenIddict.Core
         public virtual async ValueTask SetAuthorizationIdAsync(TToken token,
             string? identifier, CancellationToken cancellationToken = default)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -1047,7 +1047,7 @@ namespace OpenIddict.Core
         public virtual async ValueTask<bool> TryExtendAsync(TToken token,
             DateTimeOffset? date, CancellationToken cancellationToken = default)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -1063,7 +1063,7 @@ namespace OpenIddict.Core
             {
                 await UpdateAsync(token, cancellationToken);
 
-                if (date != null)
+                if (date is not null)
                 {
                     Logger.LogInformation(SR.GetResourceString(SR.ID7167), await Store.GetIdAsync(token, cancellationToken), date);
                 }
@@ -1099,7 +1099,7 @@ namespace OpenIddict.Core
         /// <returns><c>true</c> if the token was successfully redemeed, <c>false</c> otherwise.</returns>
         public virtual async ValueTask<bool> TryRedeemAsync(TToken token, CancellationToken cancellationToken = default)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -1144,7 +1144,7 @@ namespace OpenIddict.Core
         /// <returns><c>true</c> if the token was successfully redemeed, <c>false</c> otherwise.</returns>
         public virtual async ValueTask<bool> TryRejectAsync(TToken token, CancellationToken cancellationToken = default)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -1189,7 +1189,7 @@ namespace OpenIddict.Core
         /// <returns><c>true</c> if the token was successfully revoked, <c>false</c> otherwise.</returns>
         public virtual async ValueTask<bool> TryRevokeAsync(TToken token, CancellationToken cancellationToken = default)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -1236,7 +1236,7 @@ namespace OpenIddict.Core
         /// </returns>
         public virtual async ValueTask UpdateAsync(TToken token, CancellationToken cancellationToken = default)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -1290,12 +1290,12 @@ namespace OpenIddict.Core
         public virtual async ValueTask UpdateAsync(TToken token,
             OpenIddictTokenDescriptor descriptor, CancellationToken cancellationToken = default)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
 
-            if (descriptor == null)
+            if (descriptor is null)
             {
                 throw new ArgumentNullException(nameof(descriptor));
             }
@@ -1324,7 +1324,7 @@ namespace OpenIddict.Core
         public virtual async IAsyncEnumerable<ValidationResult> ValidateAsync(
             TToken token, [EnumeratorCancellation] CancellationToken cancellationToken = default)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -1339,7 +1339,7 @@ namespace OpenIddict.Core
                 // the casing is different). To avoid issues when the reference identifier is part of an index
                 // using the same collation, an error is added even if the two identifiers don't exactly match.
                 var other = await Store.FindByReferenceIdAsync(identifier, cancellationToken);
-                if (other != null && !string.Equals(
+                if (other is not null && !string.Equals(
                     await Store.GetIdAsync(other, cancellationToken),
                     await Store.GetIdAsync(token, cancellationToken), StringComparison.Ordinal))
                 {

src/OpenIddict.Core/OpenIddictCoreBuilder.cs

@@ -40,7 +40,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictCoreBuilder"/>.</returns>
         public OpenIddictCoreBuilder Configure(Action<OpenIddictCoreOptions> configuration)
         {
-            if (configuration == null)
+            if (configuration is null)
             {
                 throw new ArgumentNullException(nameof(configuration));
             }
@@ -74,13 +74,13 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictCoreBuilder"/>.</returns>
         public OpenIddictCoreBuilder AddApplicationStore(Type type, ServiceLifetime lifetime = ServiceLifetime.Scoped)
         {
-            if (type == null)
+            if (type is null)
             {
                 throw new ArgumentNullException(nameof(type));
             }
 
             var root = OpenIddictHelpers.FindGenericBaseType(type, typeof(IOpenIddictApplicationStore<>));
-            if (root == null)
+            if (root is null)
             {
                 throw new ArgumentException(SR.GetResourceString(SR.ID1231), nameof(type));
             }
@@ -130,13 +130,13 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictCoreBuilder"/>.</returns>
         public OpenIddictCoreBuilder AddAuthorizationStore(Type type, ServiceLifetime lifetime = ServiceLifetime.Scoped)
         {
-            if (type == null)
+            if (type is null)
             {
                 throw new ArgumentNullException(nameof(type));
             }
 
             var root = OpenIddictHelpers.FindGenericBaseType(type, typeof(IOpenIddictAuthorizationStore<>));
-            if (root == null)
+            if (root is null)
             {
                 throw new ArgumentException(SR.GetResourceString(SR.ID1231), nameof(type));
             }
@@ -186,13 +186,13 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictCoreBuilder"/>.</returns>
         public OpenIddictCoreBuilder AddScopeStore(Type type, ServiceLifetime lifetime = ServiceLifetime.Scoped)
         {
-            if (type == null)
+            if (type is null)
             {
                 throw new ArgumentNullException(nameof(type));
             }
 
             var root = OpenIddictHelpers.FindGenericBaseType(type, typeof(IOpenIddictScopeStore<>));
-            if (root == null)
+            if (root is null)
             {
                 throw new ArgumentException(SR.GetResourceString(SR.ID1231), nameof(type));
             }
@@ -242,13 +242,13 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictCoreBuilder"/>.</returns>
         public OpenIddictCoreBuilder AddTokenStore(Type type, ServiceLifetime lifetime = ServiceLifetime.Scoped)
         {
-            if (type == null)
+            if (type is null)
             {
                 throw new ArgumentNullException(nameof(type));
             }
 
             var root = OpenIddictHelpers.FindGenericBaseType(type, typeof(IOpenIddictTokenStore<>));
-            if (root == null)
+            if (root is null)
             {
                 throw new ArgumentException(SR.GetResourceString(SR.ID1231), nameof(type));
             }
@@ -296,13 +296,13 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictCoreBuilder"/>.</returns>
         public OpenIddictCoreBuilder ReplaceApplicationManager(Type type)
         {
-            if (type == null)
+            if (type is null)
             {
                 throw new ArgumentNullException(nameof(type));
             }
 
             var root = OpenIddictHelpers.FindGenericBaseType(type, typeof(OpenIddictApplicationManager<>));
-            if (root == null)
+            if (root is null)
             {
                 throw new ArgumentException(SR.GetResourceString(SR.ID1231), nameof(type));
             }
@@ -353,7 +353,7 @@ namespace Microsoft.Extensions.DependencyInjection
         public OpenIddictCoreBuilder ReplaceApplicationStoreResolver(
             Type type, ServiceLifetime lifetime = ServiceLifetime.Scoped)
         {
-            if (type == null)
+            if (type is null)
             {
                 throw new ArgumentNullException(nameof(type));
             }
@@ -390,13 +390,13 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictCoreBuilder"/>.</returns>
         public OpenIddictCoreBuilder ReplaceAuthorizationManager(Type type)
         {
-            if (type == null)
+            if (type is null)
             {
                 throw new ArgumentNullException(nameof(type));
             }
 
             var root = OpenIddictHelpers.FindGenericBaseType(type, typeof(OpenIddictAuthorizationManager<>));
-            if (root == null)
+            if (root is null)
             {
                 throw new ArgumentException(SR.GetResourceString(SR.ID1231), nameof(type));
             }
@@ -447,7 +447,7 @@ namespace Microsoft.Extensions.DependencyInjection
         public OpenIddictCoreBuilder ReplaceAuthorizationStoreResolver(
             Type type, ServiceLifetime lifetime = ServiceLifetime.Scoped)
         {
-            if (type == null)
+            if (type is null)
             {
                 throw new ArgumentNullException(nameof(type));
             }
@@ -484,13 +484,13 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictCoreBuilder"/>.</returns>
         public OpenIddictCoreBuilder ReplaceScopeManager(Type type)
         {
-            if (type == null)
+            if (type is null)
             {
                 throw new ArgumentNullException(nameof(type));
             }
 
             var root = OpenIddictHelpers.FindGenericBaseType(type, typeof(OpenIddictScopeManager<>));
-            if (root == null)
+            if (root is null)
             {
                 throw new ArgumentException(SR.GetResourceString(SR.ID1231), nameof(type));
             }
@@ -541,7 +541,7 @@ namespace Microsoft.Extensions.DependencyInjection
         public OpenIddictCoreBuilder ReplaceScopeStoreResolver(
             Type type, ServiceLifetime lifetime = ServiceLifetime.Scoped)
         {
-            if (type == null)
+            if (type is null)
             {
                 throw new ArgumentNullException(nameof(type));
             }
@@ -578,13 +578,13 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictCoreBuilder"/>.</returns>
         public OpenIddictCoreBuilder ReplaceTokenManager(Type type)
         {
-            if (type == null)
+            if (type is null)
             {
                 throw new ArgumentNullException(nameof(type));
             }
 
             var root = OpenIddictHelpers.FindGenericBaseType(type, typeof(OpenIddictTokenManager<>));
-            if (root == null)
+            if (root is null)
             {
                 throw new ArgumentException(SR.GetResourceString(SR.ID1231), nameof(type));
             }
@@ -635,7 +635,7 @@ namespace Microsoft.Extensions.DependencyInjection
         public OpenIddictCoreBuilder ReplaceTokenStoreResolver(
             Type type, ServiceLifetime lifetime = ServiceLifetime.Scoped)
         {
-            if (type == null)
+            if (type is null)
             {
                 throw new ArgumentNullException(nameof(type));
             }
@@ -684,7 +684,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictCoreBuilder"/>.</returns>
         public OpenIddictCoreBuilder SetDefaultApplicationEntity(Type type)
         {
-            if (type == null)
+            if (type is null)
             {
                 throw new ArgumentNullException(nameof(type));
             }
@@ -711,7 +711,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictCoreBuilder"/>.</returns>
         public OpenIddictCoreBuilder SetDefaultAuthorizationEntity(Type type)
         {
-            if (type == null)
+            if (type is null)
             {
                 throw new ArgumentNullException(nameof(type));
             }
@@ -738,7 +738,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictCoreBuilder"/>.</returns>
         public OpenIddictCoreBuilder SetDefaultScopeEntity(Type type)
         {
-            if (type == null)
+            if (type is null)
             {
                 throw new ArgumentNullException(nameof(type));
             }
@@ -765,7 +765,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictCoreBuilder"/>.</returns>
         public OpenIddictCoreBuilder SetDefaultTokenEntity(Type type)
         {
-            if (type == null)
+            if (type is null)
             {
                 throw new ArgumentNullException(nameof(type));
             }

src/OpenIddict.Core/OpenIddictCoreExtensions.cs

@@ -29,7 +29,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictBuilder"/>.</returns>
         public static OpenIddictCoreBuilder AddCore(this OpenIddictBuilder builder)
         {
-            if (builder == null)
+            if (builder is null)
             {
                 throw new ArgumentNullException(nameof(builder));
             }
@@ -57,7 +57,7 @@ namespace Microsoft.Extensions.DependencyInjection
             builder.Services.TryAddScoped(provider =>
             {
                 var options = provider.GetRequiredService<IOptionsMonitor<OpenIddictCoreOptions>>().CurrentValue;
-                if (options.DefaultApplicationType == null)
+                if (options.DefaultApplicationType is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1272));
                 }
@@ -69,7 +69,7 @@ namespace Microsoft.Extensions.DependencyInjection
             builder.Services.TryAddScoped(provider =>
             {
                 var options = provider.GetRequiredService<IOptionsMonitor<OpenIddictCoreOptions>>().CurrentValue;
-                if (options.DefaultAuthorizationType == null)
+                if (options.DefaultAuthorizationType is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1273));
                 }
@@ -81,7 +81,7 @@ namespace Microsoft.Extensions.DependencyInjection
             builder.Services.TryAddScoped(provider =>
             {
                 var options = provider.GetRequiredService<IOptionsMonitor<OpenIddictCoreOptions>>().CurrentValue;
-                if (options.DefaultScopeType == null)
+                if (options.DefaultScopeType is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1274));
                 }
@@ -93,7 +93,7 @@ namespace Microsoft.Extensions.DependencyInjection
             builder.Services.TryAddScoped(provider =>
             {
                 var options = provider.GetRequiredService<IOptionsMonitor<OpenIddictCoreOptions>>().CurrentValue;
-                if (options.DefaultTokenType == null)
+                if (options.DefaultTokenType is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1275));
                 }
@@ -126,12 +126,12 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictBuilder"/>.</returns>
         public static OpenIddictBuilder AddCore(this OpenIddictBuilder builder, Action<OpenIddictCoreBuilder> configuration)
         {
-            if (builder == null)
+            if (builder is null)
             {
                 throw new ArgumentNullException(nameof(builder));
             }
 
-            if (configuration == null)
+            if (configuration is null)
             {
                 throw new ArgumentNullException(nameof(configuration));
             }

src/OpenIddict.EntityFramework/OpenIddictEntityFrameworkBuilder.cs

@@ -41,7 +41,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictEntityFrameworkBuilder"/>.</returns>
         public OpenIddictEntityFrameworkBuilder Configure(Action<OpenIddictEntityFrameworkOptions> configuration)
         {
-            if (configuration == null)
+            if (configuration is null)
             {
                 throw new ArgumentNullException(nameof(configuration));
             }
@@ -99,7 +99,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictEntityFrameworkBuilder"/>.</returns>
         public OpenIddictEntityFrameworkBuilder UseDbContext(Type type)
         {
-            if (type == null)
+            if (type is null)
             {
                 throw new ArgumentNullException(nameof(type));
             }

src/OpenIddict.EntityFramework/OpenIddictEntityFrameworkExtensions.cs

@@ -25,7 +25,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictEntityFrameworkBuilder"/>.</returns>
         public static OpenIddictEntityFrameworkBuilder UseEntityFramework(this OpenIddictCoreBuilder builder)
         {
-            if (builder == null)
+            if (builder is null)
             {
                 throw new ArgumentNullException(nameof(builder));
             }
@@ -69,12 +69,12 @@ namespace Microsoft.Extensions.DependencyInjection
         public static OpenIddictCoreBuilder UseEntityFramework(
             this OpenIddictCoreBuilder builder, Action<OpenIddictEntityFrameworkBuilder> configuration)
         {
-            if (builder == null)
+            if (builder is null)
             {
                 throw new ArgumentNullException(nameof(builder));
             }
 
-            if (configuration == null)
+            if (configuration is null)
             {
                 throw new ArgumentNullException(nameof(configuration));
             }

src/OpenIddict.EntityFramework/OpenIddictEntityFrameworkHelpers.cs

@@ -48,7 +48,7 @@ namespace System.Data.Entity
             where TToken : OpenIddictEntityFrameworkToken<TKey, TApplication, TAuthorization>
             where TKey : IEquatable<TKey>
         {
-            if (builder == null)
+            if (builder is null)
             {
                 throw new ArgumentNullException(nameof(builder));
             }
@@ -71,7 +71,7 @@ namespace System.Data.Entity
         /// <returns>The non-streamed async enumeration containing the results.</returns>
         internal static IAsyncEnumerable<T> AsAsyncEnumerable<T>(this IQueryable<T> source, CancellationToken cancellationToken)
         {
-            if (source == null)
+            if (source is null)
             {
                 throw new ArgumentNullException(nameof(source));
             }

src/OpenIddict.EntityFramework/Resolvers/OpenIddictEntityFrameworkApplicationStoreResolver.cs

@@ -43,7 +43,7 @@ namespace OpenIddict.EntityFramework
         public IOpenIddictApplicationStore<TApplication> Get<TApplication>() where TApplication : class
         {
             var store = _provider.GetService<IOpenIddictApplicationStore<TApplication>>();
-            if (store != null)
+            if (store is not null)
             {
                 return store;
             }
@@ -51,13 +51,13 @@ namespace OpenIddict.EntityFramework
             var type = _cache.GetOrAdd(typeof(TApplication), key =>
             {
                 var root = OpenIddictHelpers.FindGenericBaseType(key, typeof(OpenIddictEntityFrameworkApplication<,,>));
-                if (root == null)
+                if (root is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1233));
                 }
 
                 var context = _options.CurrentValue.DbContextType;
-                if (context == null)
+                if (context is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1234));
                 }

src/OpenIddict.EntityFramework/Resolvers/OpenIddictEntityFrameworkAuthorizationStoreResolver.cs

@@ -43,7 +43,7 @@ namespace OpenIddict.EntityFramework
         public IOpenIddictAuthorizationStore<TAuthorization> Get<TAuthorization>() where TAuthorization : class
         {
             var store = _provider.GetService<IOpenIddictAuthorizationStore<TAuthorization>>();
-            if (store != null)
+            if (store is not null)
             {
                 return store;
             }
@@ -51,13 +51,13 @@ namespace OpenIddict.EntityFramework
             var type = _cache.GetOrAdd(typeof(TAuthorization), key =>
             {
                 var root = OpenIddictHelpers.FindGenericBaseType(key, typeof(OpenIddictEntityFrameworkAuthorization<,,>));
-                if (root == null)
+                if (root is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1235));
                 }
 
                 var context = _options.CurrentValue.DbContextType;
-                if (context == null)
+                if (context is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1234));
                 }

src/OpenIddict.EntityFramework/Resolvers/OpenIddictEntityFrameworkScopeStoreResolver.cs

@@ -43,7 +43,7 @@ namespace OpenIddict.EntityFramework
         public IOpenIddictScopeStore<TScope> Get<TScope>() where TScope : class
         {
             var store = _provider.GetService<IOpenIddictScopeStore<TScope>>();
-            if (store != null)
+            if (store is not null)
             {
                 return store;
             }
@@ -51,13 +51,13 @@ namespace OpenIddict.EntityFramework
             var type = _cache.GetOrAdd(typeof(TScope), key =>
             {
                 var root = OpenIddictHelpers.FindGenericBaseType(key, typeof(OpenIddictEntityFrameworkScope<>));
-                if (root == null)
+                if (root is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1236));
                 }
 
                 var context = _options.CurrentValue.DbContextType;
-                if (context == null)
+                if (context is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1234));
                 }

src/OpenIddict.EntityFramework/Resolvers/OpenIddictEntityFrameworkTokenStoreResolver.cs

@@ -43,7 +43,7 @@ namespace OpenIddict.EntityFramework
         public IOpenIddictTokenStore<TToken> Get<TToken>() where TToken : class
         {
             var store = _provider.GetService<IOpenIddictTokenStore<TToken>>();
-            if (store != null)
+            if (store is not null)
             {
                 return store;
             }
@@ -51,13 +51,13 @@ namespace OpenIddict.EntityFramework
             var type = _cache.GetOrAdd(typeof(TToken), key =>
             {
                 var root = OpenIddictHelpers.FindGenericBaseType(key, typeof(OpenIddictEntityFrameworkToken<,,>));
-                if (root == null)
+                if (root is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1237));
                 }
 
                 var context = _options.CurrentValue.DbContextType;
-                if (context == null)
+                if (context is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1234));
                 }

src/OpenIddict.EntityFramework/Stores/OpenIddictEntityFrameworkApplicationStore.cs

@@ -109,7 +109,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual async ValueTask<long> CountAsync<TResult>(Func<IQueryable<TApplication>, IQueryable<TResult>> query, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -120,7 +120,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual async ValueTask CreateAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -133,7 +133,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual async ValueTask DeleteAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -315,7 +315,7 @@ namespace OpenIddict.EntityFramework
             Func<IQueryable<TApplication>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -326,7 +326,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetClientIdAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -337,7 +337,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetClientSecretAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -348,7 +348,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetClientTypeAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -359,7 +359,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetConsentTypeAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -370,7 +370,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetDisplayNameAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -381,7 +381,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableDictionary<CultureInfo, string>> GetDisplayNamesAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -409,7 +409,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetIdAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -420,7 +420,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableArray<string>> GetPermissionsAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -447,7 +447,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableArray<string>> GetPostLogoutRedirectUrisAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -474,7 +474,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableDictionary<string, JsonElement>> GetPropertiesAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -501,7 +501,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableArray<string>> GetRedirectUrisAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -528,7 +528,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableArray<string>> GetRequirementsAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -591,7 +591,7 @@ namespace OpenIddict.EntityFramework
             Func<IQueryable<TApplication>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -602,7 +602,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask SetClientIdAsync(TApplication application, string? identifier, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -615,7 +615,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask SetClientSecretAsync(TApplication application, string? secret, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -628,7 +628,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask SetClientTypeAsync(TApplication application, string? type, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -641,7 +641,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask SetConsentTypeAsync(TApplication application, string? type, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -654,7 +654,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask SetDisplayNameAsync(TApplication application, string? name, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -668,12 +668,12 @@ namespace OpenIddict.EntityFramework
         public virtual ValueTask SetDisplayNamesAsync(TApplication application,
             ImmutableDictionary<CultureInfo, string> names, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
 
-            if (names == null || names.IsEmpty)
+            if (names is null || names.IsEmpty)
             {
                 application.DisplayNames = null;
 
@@ -706,7 +706,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask SetPermissionsAsync(TApplication application, ImmutableArray<string> permissions, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -731,7 +731,7 @@ namespace OpenIddict.EntityFramework
         public virtual ValueTask SetPostLogoutRedirectUrisAsync(TApplication application,
             ImmutableArray<string> addresses, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -756,12 +756,12 @@ namespace OpenIddict.EntityFramework
         public virtual ValueTask SetPropertiesAsync(TApplication application,
             ImmutableDictionary<string, JsonElement> properties, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
 
-            if (properties == null || properties.IsEmpty)
+            if (properties is null || properties.IsEmpty)
             {
                 application.Properties = null;
 
@@ -781,7 +781,7 @@ namespace OpenIddict.EntityFramework
         public virtual ValueTask SetRedirectUrisAsync(TApplication application,
             ImmutableArray<string> addresses, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -805,7 +805,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask SetRequirementsAsync(TApplication application, ImmutableArray<string> requirements, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -829,7 +829,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual async ValueTask UpdateAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }

src/OpenIddict.EntityFramework/Stores/OpenIddictEntityFrameworkAuthorizationStore.cs

@@ -106,7 +106,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual async ValueTask<long> CountAsync<TResult>(Func<IQueryable<TAuthorization>, IQueryable<TResult>> query, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -117,7 +117,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual async ValueTask CreateAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -130,7 +130,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual async ValueTask DeleteAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -204,8 +204,7 @@ namespace OpenIddict.EntityFramework
             var key = ConvertIdentifierFromString(client);
 
             return (from authorization in Authorizations.Include(authorization => authorization.Application)
-                    where authorization.Application != null &&
-                          authorization.Application.Id!.Equals(key) &&
+                    where authorization.Application!.Id!.Equals(key) &&
                           authorization.Subject == subject
                     select authorization).AsAsyncEnumerable(cancellationToken);
         }
@@ -233,8 +232,7 @@ namespace OpenIddict.EntityFramework
             var key = ConvertIdentifierFromString(client);
 
             return (from authorization in Authorizations.Include(authorization => authorization.Application)
-                    where authorization.Application != null &&
-                          authorization.Application.Id!.Equals(key) &&
+                    where authorization.Application!.Id!.Equals(key) &&
                           authorization.Subject == subject &&
                           authorization.Status == status
                     select authorization).AsAsyncEnumerable(cancellationToken);
@@ -268,8 +266,7 @@ namespace OpenIddict.EntityFramework
             var key = ConvertIdentifierFromString(client);
 
             return (from authorization in Authorizations.Include(authorization => authorization.Application)
-                    where authorization.Application != null &&
-                          authorization.Application.Id!.Equals(key) &&
+                    where authorization.Application!.Id!.Equals(key) &&
                           authorization.Subject == subject &&
                           authorization.Status == status &&
                           authorization.Type == type
@@ -309,8 +306,7 @@ namespace OpenIddict.EntityFramework
                 var key = ConvertIdentifierFromString(client);
 
                 var authorizations = (from authorization in Authorizations.Include(authorization => authorization.Application)
-                                      where authorization.Application != null &&
-                                            authorization.Application.Id!.Equals(key) &&
+                                      where authorization.Application!.Id!.Equals(key) &&
                                             authorization.Subject == subject &&
                                             authorization.Status == status &&
                                             authorization.Type == type
@@ -374,13 +370,13 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual async ValueTask<string?> GetApplicationIdAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
 
             // If the application is not attached to the authorization, try to load it manually.
-            if (authorization.Application == null)
+            if (authorization.Application is null)
             {
                 var reference = Context.Entry(authorization).Reference(entry => entry.Application);
                 if (reference.EntityEntry.State == EntityState.Detached)
@@ -391,7 +387,7 @@ namespace OpenIddict.EntityFramework
                 await reference.LoadAsync(cancellationToken);
             }
 
-            if (authorization.Application == null)
+            if (authorization.Application is null)
             {
                 return null;
             }
@@ -404,7 +400,7 @@ namespace OpenIddict.EntityFramework
             Func<IQueryable<TAuthorization>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -416,7 +412,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<DateTimeOffset?> GetCreationDateAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -427,7 +423,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetIdAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -438,7 +434,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableDictionary<string, JsonElement>> GetPropertiesAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -465,7 +461,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableArray<string>> GetScopesAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -492,7 +488,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetStatusAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -503,7 +499,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetSubjectAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -514,7 +510,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetTypeAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -562,7 +558,7 @@ namespace OpenIddict.EntityFramework
             Func<IQueryable<TAuthorization>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -637,7 +633,7 @@ namespace OpenIddict.EntityFramework
                 }
             }
 
-            if (exceptions != null)
+            if (exceptions is not null)
             {
                 throw new AggregateException(SR.GetResourceString(SR.ID1242), exceptions);
             }
@@ -647,7 +643,7 @@ namespace OpenIddict.EntityFramework
         public virtual async ValueTask SetApplicationIdAsync(TAuthorization authorization,
             string? identifier, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -655,7 +651,7 @@ namespace OpenIddict.EntityFramework
             if (!string.IsNullOrEmpty(identifier))
             {
                 var application = await Applications.FindAsync(cancellationToken, ConvertIdentifierFromString(identifier));
-                if (application == null)
+                if (application is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1243));
                 }
@@ -666,7 +662,7 @@ namespace OpenIddict.EntityFramework
             else
             {
                 // If the application is not attached to the authorization, try to load it manually.
-                if (authorization.Application == null)
+                if (authorization.Application is null)
                 {
                     var reference = Context.Entry(authorization).Reference(entry => entry.Application);
                     if (reference.EntityEntry.State == EntityState.Detached)
@@ -685,7 +681,7 @@ namespace OpenIddict.EntityFramework
         public virtual ValueTask SetCreationDateAsync(TAuthorization authorization,
             DateTimeOffset? date, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -699,12 +695,12 @@ namespace OpenIddict.EntityFramework
         public virtual ValueTask SetPropertiesAsync(TAuthorization authorization,
             ImmutableDictionary<string, JsonElement> properties, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
 
-            if (properties == null || properties.IsEmpty)
+            if (properties is null || properties.IsEmpty)
             {
                 authorization.Properties = null;
 
@@ -724,7 +720,7 @@ namespace OpenIddict.EntityFramework
         public virtual ValueTask SetScopesAsync(TAuthorization authorization,
             ImmutableArray<string> scopes, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -748,7 +744,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask SetStatusAsync(TAuthorization authorization, string? status, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -761,7 +757,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask SetSubjectAsync(TAuthorization authorization, string? subject, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -774,7 +770,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask SetTypeAsync(TAuthorization authorization, string? type, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -787,7 +783,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual async ValueTask UpdateAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }

src/OpenIddict.EntityFramework/Stores/OpenIddictEntityFrameworkScopeStore.cs

@@ -92,7 +92,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual async ValueTask<long> CountAsync<TResult>(Func<IQueryable<TScope>, IQueryable<TResult>> query, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -103,7 +103,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual async ValueTask CreateAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -116,7 +116,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual async ValueTask DeleteAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -220,7 +220,7 @@ namespace OpenIddict.EntityFramework
             Func<IQueryable<TScope>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -231,7 +231,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetDescriptionAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -242,7 +242,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableDictionary<CultureInfo, string>> GetDescriptionsAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -270,7 +270,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetDisplayNameAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -281,7 +281,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableDictionary<CultureInfo, string>> GetDisplayNamesAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -309,7 +309,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetIdAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -320,7 +320,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetNameAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -331,7 +331,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableDictionary<string, JsonElement>> GetPropertiesAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -358,7 +358,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableArray<string>> GetResourcesAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -420,7 +420,7 @@ namespace OpenIddict.EntityFramework
             Func<IQueryable<TScope>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -431,7 +431,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask SetDescriptionAsync(TScope scope, string? description, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -445,12 +445,12 @@ namespace OpenIddict.EntityFramework
         public virtual ValueTask SetDescriptionsAsync(TScope scope,
             ImmutableDictionary<CultureInfo, string> descriptions, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
 
-            if (descriptions == null || descriptions.IsEmpty)
+            if (descriptions is null || descriptions.IsEmpty)
             {
                 scope.Descriptions = null;
 
@@ -483,7 +483,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask SetDisplayNameAsync(TScope scope, string? name, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -497,12 +497,12 @@ namespace OpenIddict.EntityFramework
         public virtual ValueTask SetDisplayNamesAsync(TScope scope,
             ImmutableDictionary<CultureInfo, string> names, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
 
-            if (names == null || names.IsEmpty)
+            if (names is null || names.IsEmpty)
             {
                 scope.DisplayNames = null;
 
@@ -535,7 +535,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask SetNameAsync(TScope scope, string? name, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -549,12 +549,12 @@ namespace OpenIddict.EntityFramework
         public virtual ValueTask SetPropertiesAsync(TScope scope,
             ImmutableDictionary<string, JsonElement> properties, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
 
-            if (properties == null || properties.IsEmpty)
+            if (properties is null || properties.IsEmpty)
             {
                 scope.Properties = null;
 
@@ -573,7 +573,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask SetResourcesAsync(TScope scope, ImmutableArray<string> resources, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -597,7 +597,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual async ValueTask UpdateAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }

src/OpenIddict.EntityFramework/Stores/OpenIddictEntityFrameworkTokenStore.cs

@@ -106,7 +106,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual async ValueTask<long> CountAsync<TResult>(Func<IQueryable<TToken>, IQueryable<TResult>> query, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -117,7 +117,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual async ValueTask CreateAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -130,7 +130,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual async ValueTask DeleteAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -168,8 +168,7 @@ namespace OpenIddict.EntityFramework
             var key = ConvertIdentifierFromString(client);
 
             return (from token in Tokens.Include(token => token.Application).Include(token => token.Authorization)
-                    where token.Application != null &&
-                          token.Application.Id!.Equals(key) &&
+                    where token.Application!.Id!.Equals(key) &&
                           token.Subject == subject
                     select token).AsAsyncEnumerable(cancellationToken);
         }
@@ -197,8 +196,7 @@ namespace OpenIddict.EntityFramework
             var key = ConvertIdentifierFromString(client);
 
             return (from token in Tokens.Include(token => token.Application).Include(token => token.Authorization)
-                    where token.Application != null &&
-                          token.Application.Id!.Equals(key) &&
+                    where token.Application!.Id!.Equals(key) &&
                           token.Subject == subject &&
                           token.Status == status
                     select token).AsAsyncEnumerable(cancellationToken);
@@ -232,8 +230,7 @@ namespace OpenIddict.EntityFramework
             var key = ConvertIdentifierFromString(client);
 
             return (from token in Tokens.Include(token => token.Application).Include(token => token.Authorization)
-                    where token.Application != null &&
-                          token.Application.Id!.Equals(key) &&
+                    where token.Application!.Id!.Equals(key) &&
                           token.Subject == subject &&
                           token.Status == status &&
                           token.Type == type
@@ -251,8 +248,7 @@ namespace OpenIddict.EntityFramework
             var key = ConvertIdentifierFromString(identifier);
 
             return (from token in Tokens.Include(token => token.Application).Include(token => token.Authorization)
-                    where token.Application != null &&
-                          token.Application.Id!.Equals(key)
+                    where token.Application!.Id!.Equals(key)
                     select token).AsAsyncEnumerable(cancellationToken);
         }
 
@@ -267,8 +263,7 @@ namespace OpenIddict.EntityFramework
             var key = ConvertIdentifierFromString(identifier);
 
             return (from token in Tokens.Include(token => token.Application).Include(token => token.Authorization)
-                    where token.Authorization != null &&
-                          token.Authorization.Id!.Equals(key)
+                    where token.Authorization!.Id!.Equals(key)
                     select token).AsAsyncEnumerable(cancellationToken);
         }
 
@@ -316,13 +311,13 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual async ValueTask<string?> GetApplicationIdAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
 
             // If the application is not attached to the token, try to load it manually.
-            if (token.Application == null)
+            if (token.Application is null)
             {
                 var reference = Context.Entry(token).Reference(entry => entry.Application);
                 if (reference.EntityEntry.State == EntityState.Detached)
@@ -333,7 +328,7 @@ namespace OpenIddict.EntityFramework
                 await reference.LoadAsync(cancellationToken);
             }
 
-            if (token.Application == null)
+            if (token.Application is null)
             {
                 return null;
             }
@@ -346,7 +341,7 @@ namespace OpenIddict.EntityFramework
             Func<IQueryable<TToken>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -359,13 +354,13 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual async ValueTask<string?> GetAuthorizationIdAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
 
             // If the authorization is not attached to the token, try to load it manually.
-            if (token.Authorization == null)
+            if (token.Authorization is null)
             {
                 var reference = Context.Entry(token).Reference(entry => entry.Authorization);
                 if (reference.EntityEntry.State == EntityState.Detached)
@@ -376,7 +371,7 @@ namespace OpenIddict.EntityFramework
                 await reference.LoadAsync(cancellationToken);
             }
 
-            if (token.Authorization == null)
+            if (token.Authorization is null)
             {
                 return null;
             }
@@ -387,7 +382,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<DateTimeOffset?> GetCreationDateAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -398,7 +393,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<DateTimeOffset?> GetExpirationDateAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -409,7 +404,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetIdAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -420,7 +415,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetPayloadAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -431,7 +426,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableDictionary<string, JsonElement>> GetPropertiesAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -458,7 +453,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetReferenceIdAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -469,7 +464,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetStatusAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -480,7 +475,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetSubjectAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -491,7 +486,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetTypeAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -540,7 +535,7 @@ namespace OpenIddict.EntityFramework
             Func<IQueryable<TToken>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -616,7 +611,7 @@ namespace OpenIddict.EntityFramework
                 }
             }
 
-            if (exceptions != null)
+            if (exceptions is not null)
             {
                 throw new AggregateException(SR.GetResourceString(SR.ID1248), exceptions);
             }
@@ -625,7 +620,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual async ValueTask SetApplicationIdAsync(TToken token, string? identifier, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -633,7 +628,7 @@ namespace OpenIddict.EntityFramework
             if (!string.IsNullOrEmpty(identifier))
             {
                 var application = await Applications.FindAsync(cancellationToken, ConvertIdentifierFromString(identifier));
-                if (application == null)
+                if (application is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1249));
                 }
@@ -644,7 +639,7 @@ namespace OpenIddict.EntityFramework
             else
             {
                 // If the application is not attached to the token, try to load it manually.
-                if (token.Application == null)
+                if (token.Application is null)
                 {
                     var reference = Context.Entry(token).Reference(entry => entry.Application);
                     if (reference.EntityEntry.State == EntityState.Detached)
@@ -662,7 +657,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual async ValueTask SetAuthorizationIdAsync(TToken token, string? identifier, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -670,7 +665,7 @@ namespace OpenIddict.EntityFramework
             if (!string.IsNullOrEmpty(identifier))
             {
                 var authorization = await Authorizations.FindAsync(cancellationToken, ConvertIdentifierFromString(identifier));
-                if (authorization == null)
+                if (authorization is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1250));
                 }
@@ -681,7 +676,7 @@ namespace OpenIddict.EntityFramework
             else
             {
                 // If the authorization is not attached to the token, try to load it manually.
-                if (token.Authorization == null)
+                if (token.Authorization is null)
                 {
                     var reference = Context.Entry(token).Reference(entry => entry.Authorization);
                     if (reference.EntityEntry.State == EntityState.Detached)
@@ -699,7 +694,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask SetCreationDateAsync(TToken token, DateTimeOffset? date, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -712,7 +707,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask SetExpirationDateAsync(TToken token, DateTimeOffset? date, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -725,7 +720,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask SetPayloadAsync(TToken token, string? payload, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -739,12 +734,12 @@ namespace OpenIddict.EntityFramework
         public virtual ValueTask SetPropertiesAsync(TToken token,
             ImmutableDictionary<string, JsonElement> properties, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
 
-            if (properties == null || properties.IsEmpty)
+            if (properties is null || properties.IsEmpty)
             {
                 token.Properties = null;
 
@@ -763,7 +758,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask SetReferenceIdAsync(TToken token, string? identifier, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -776,7 +771,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask SetStatusAsync(TToken token, string? status, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -789,7 +784,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask SetSubjectAsync(TToken token, string? subject, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -802,7 +797,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual ValueTask SetTypeAsync(TToken token, string? type, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -815,7 +810,7 @@ namespace OpenIddict.EntityFramework
         /// <inheritdoc/>
         public virtual async ValueTask UpdateAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }

src/OpenIddict.EntityFrameworkCore/Configurations/OpenIddictEntityFrameworkCoreApplicationConfiguration.cs

@@ -28,7 +28,7 @@ namespace OpenIddict.EntityFrameworkCore
     {
         public void Configure(EntityTypeBuilder<TApplication> builder)
         {
-            if (builder == null)
+            if (builder is null)
             {
                 throw new ArgumentNullException(nameof(builder));
             }

src/OpenIddict.EntityFrameworkCore/Configurations/OpenIddictEntityFrameworkCoreAuthorizationConfiguration.cs

@@ -28,7 +28,7 @@ namespace OpenIddict.EntityFrameworkCore
     {
         public void Configure(EntityTypeBuilder<TAuthorization> builder)
         {
-            if (builder == null)
+            if (builder is null)
             {
                 throw new ArgumentNullException(nameof(builder));
             }

src/OpenIddict.EntityFrameworkCore/Configurations/OpenIddictEntityFrameworkCoreScopeConfiguration.cs

@@ -24,7 +24,7 @@ namespace OpenIddict.EntityFrameworkCore
     {
         public void Configure(EntityTypeBuilder<TScope> builder)
         {
-            if (builder == null)
+            if (builder is null)
             {
                 throw new ArgumentNullException(nameof(builder));
             }

src/OpenIddict.EntityFrameworkCore/Configurations/OpenIddictEntityFrameworkCoreTokenConfiguration.cs

@@ -28,7 +28,7 @@ namespace OpenIddict.EntityFrameworkCore
     {
         public void Configure(EntityTypeBuilder<TToken> builder)
         {
-            if (builder == null)
+            if (builder is null)
             {
                 throw new ArgumentNullException(nameof(builder));
             }

src/OpenIddict.EntityFrameworkCore/OpenIddictEntityFrameworkCoreBuilder.cs

@@ -40,7 +40,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictEntityFrameworkCoreBuilder"/>.</returns>
         public OpenIddictEntityFrameworkCoreBuilder Configure(Action<OpenIddictEntityFrameworkCoreOptions> configuration)
         {
-            if (configuration == null)
+            if (configuration is null)
             {
                 throw new ArgumentNullException(nameof(configuration));
             }
@@ -101,7 +101,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictEntityFrameworkCoreBuilder"/>.</returns>
         public OpenIddictEntityFrameworkCoreBuilder UseDbContext(Type type)
         {
-            if (type == null)
+            if (type is null)
             {
                 throw new ArgumentNullException(nameof(type));
             }

src/OpenIddict.EntityFrameworkCore/OpenIddictEntityFrameworkCoreCustomizer.cs

@@ -29,12 +29,12 @@ namespace OpenIddict.EntityFrameworkCore
 
         public override void Customize(ModelBuilder modelBuilder, DbContext context)
         {
-            if (modelBuilder == null)
+            if (modelBuilder is null)
             {
                 throw new ArgumentNullException(nameof(modelBuilder));
             }
 
-            if (context == null)
+            if (context is null)
             {
                 throw new ArgumentNullException(nameof(context));
             }

src/OpenIddict.EntityFrameworkCore/OpenIddictEntityFrameworkCoreExtensions.cs

@@ -25,7 +25,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictEntityFrameworkCoreBuilder"/>.</returns>
         public static OpenIddictEntityFrameworkCoreBuilder UseEntityFrameworkCore(this OpenIddictCoreBuilder builder)
         {
-            if (builder == null)
+            if (builder is null)
             {
                 throw new ArgumentNullException(nameof(builder));
             }
@@ -69,12 +69,12 @@ namespace Microsoft.Extensions.DependencyInjection
         public static OpenIddictCoreBuilder UseEntityFrameworkCore(
             this OpenIddictCoreBuilder builder, Action<OpenIddictEntityFrameworkCoreBuilder> configuration)
         {
-            if (builder == null)
+            if (builder is null)
             {
                 throw new ArgumentNullException(nameof(builder));
             }
 
-            if (configuration == null)
+            if (configuration is null)
             {
                 throw new ArgumentNullException(nameof(configuration));
             }

src/OpenIddict.EntityFrameworkCore/OpenIddictEntityFrameworkCoreHelpers.cs

@@ -68,7 +68,7 @@ namespace Microsoft.EntityFrameworkCore
             where TToken : OpenIddictEntityFrameworkCoreToken<TKey, TApplication, TAuthorization>
             where TKey : IEquatable<TKey>
         {
-            if (builder == null)
+            if (builder is null)
             {
                 throw new ArgumentNullException(nameof(builder));
             }
@@ -122,7 +122,7 @@ namespace Microsoft.EntityFrameworkCore
             where TToken : OpenIddictEntityFrameworkCoreToken<TKey, TApplication, TAuthorization>
             where TKey : IEquatable<TKey>
         {
-            if (builder == null)
+            if (builder is null)
             {
                 throw new ArgumentNullException(nameof(builder));
             }
@@ -145,7 +145,7 @@ namespace Microsoft.EntityFrameworkCore
         internal static IAsyncEnumerable<T> AsAsyncEnumerable<T>(
             this IQueryable<T> source, CancellationToken cancellationToken = default)
         {
-            if (source == null)
+            if (source is null)
             {
                 throw new ArgumentNullException(nameof(source));
             }

src/OpenIddict.EntityFrameworkCore/Resolvers/OpenIddictEntityFrameworkCoreApplicationStoreResolver.cs

@@ -43,7 +43,7 @@ namespace OpenIddict.EntityFrameworkCore
         public IOpenIddictApplicationStore<TApplication> Get<TApplication>() where TApplication : class
         {
             var store = _provider.GetService<IOpenIddictApplicationStore<TApplication>>();
-            if (store != null)
+            if (store is not null)
             {
                 return store;
             }
@@ -51,13 +51,13 @@ namespace OpenIddict.EntityFrameworkCore
             var type = _cache.GetOrAdd(typeof(TApplication), key =>
             {
                 var root = OpenIddictHelpers.FindGenericBaseType(key, typeof(OpenIddictEntityFrameworkCoreApplication<,,>));
-                if (root == null)
+                if (root is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1251));
                 }
 
                 var context = _options.CurrentValue.DbContextType;
-                if (context == null)
+                if (context is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1252));
                 }

src/OpenIddict.EntityFrameworkCore/Resolvers/OpenIddictEntityFrameworkCoreAuthorizationStoreResolver.cs

@@ -43,7 +43,7 @@ namespace OpenIddict.EntityFrameworkCore
         public IOpenIddictAuthorizationStore<TAuthorization> Get<TAuthorization>() where TAuthorization : class
         {
             var store = _provider.GetService<IOpenIddictAuthorizationStore<TAuthorization>>();
-            if (store != null)
+            if (store is not null)
             {
                 return store;
             }
@@ -51,13 +51,13 @@ namespace OpenIddict.EntityFrameworkCore
             var type = _cache.GetOrAdd(typeof(TAuthorization), key =>
             {
                 var root = OpenIddictHelpers.FindGenericBaseType(key, typeof(OpenIddictEntityFrameworkCoreAuthorization<,,>));
-                if (root == null)
+                if (root is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1253));
                 }
 
                 var context = _options.CurrentValue.DbContextType;
-                if (context == null)
+                if (context is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1252));
                 }

src/OpenIddict.EntityFrameworkCore/Resolvers/OpenIddictEntityFrameworkCoreScopeStoreResolver.cs

@@ -43,7 +43,7 @@ namespace OpenIddict.EntityFrameworkCore
         public IOpenIddictScopeStore<TScope> Get<TScope>() where TScope : class
         {
             var store = _provider.GetService<IOpenIddictScopeStore<TScope>>();
-            if (store != null)
+            if (store is not null)
             {
                 return store;
             }
@@ -51,13 +51,13 @@ namespace OpenIddict.EntityFrameworkCore
             var type = _cache.GetOrAdd(typeof(TScope), key =>
             {
                 var root = OpenIddictHelpers.FindGenericBaseType(key, typeof(OpenIddictEntityFrameworkCoreScope<>));
-                if (root == null)
+                if (root is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1254));
                 }
 
                 var context = _options.CurrentValue.DbContextType;
-                if (context == null)
+                if (context is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1252));
                 }

src/OpenIddict.EntityFrameworkCore/Resolvers/OpenIddictEntityFrameworkCoreTokenStoreResolver.cs

@@ -43,7 +43,7 @@ namespace OpenIddict.EntityFrameworkCore
         public IOpenIddictTokenStore<TToken> Get<TToken>() where TToken : class
         {
             var store = _provider.GetService<IOpenIddictTokenStore<TToken>>();
-            if (store != null)
+            if (store is not null)
             {
                 return store;
             }
@@ -51,13 +51,13 @@ namespace OpenIddict.EntityFrameworkCore
             var type = _cache.GetOrAdd(typeof(TToken), key =>
             {
                 var root = OpenIddictHelpers.FindGenericBaseType(key, typeof(OpenIddictEntityFrameworkCoreToken<,,>));
-                if (root == null)
+                if (root is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1255));
                 }
 
                 var context = _options.CurrentValue.DbContextType;
-                if (context == null)
+                if (context is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1252));
                 }

src/OpenIddict.EntityFrameworkCore/Stores/OpenIddictEntityFrameworkCoreApplicationStore.cs

@@ -138,7 +138,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual async ValueTask<long> CountAsync<TResult>(Func<IQueryable<TApplication>, IQueryable<TResult>> query, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -149,7 +149,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual async ValueTask CreateAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -162,7 +162,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual async ValueTask DeleteAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -366,7 +366,7 @@ namespace OpenIddict.EntityFrameworkCore
             Func<IQueryable<TApplication>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -377,7 +377,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetClientIdAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -388,7 +388,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetClientSecretAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -399,7 +399,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetClientTypeAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -410,7 +410,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetConsentTypeAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -421,7 +421,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetDisplayNameAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -432,7 +432,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableDictionary<CultureInfo, string>> GetDisplayNamesAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -460,7 +460,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetIdAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -471,7 +471,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableArray<string>> GetPermissionsAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -498,7 +498,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableArray<string>> GetPostLogoutRedirectUrisAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -525,7 +525,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableDictionary<string, JsonElement>> GetPropertiesAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -552,7 +552,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableArray<string>> GetRedirectUrisAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -579,7 +579,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableArray<string>> GetRequirementsAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -641,7 +641,7 @@ namespace OpenIddict.EntityFrameworkCore
             Func<IQueryable<TApplication>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -652,7 +652,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask SetClientIdAsync(TApplication application, string? identifier, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -665,7 +665,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask SetClientSecretAsync(TApplication application, string? secret, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -678,7 +678,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask SetClientTypeAsync(TApplication application, string? type, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -691,7 +691,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask SetConsentTypeAsync(TApplication application, string? type, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -704,7 +704,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask SetDisplayNameAsync(TApplication application, string? name, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -718,12 +718,12 @@ namespace OpenIddict.EntityFrameworkCore
         public virtual ValueTask SetDisplayNamesAsync(TApplication application,
             ImmutableDictionary<CultureInfo, string> names, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
 
-            if (names == null || names.IsEmpty)
+            if (names is null || names.IsEmpty)
             {
                 application.DisplayNames = null;
 
@@ -756,7 +756,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask SetPermissionsAsync(TApplication application, ImmutableArray<string> permissions, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -781,7 +781,7 @@ namespace OpenIddict.EntityFrameworkCore
         public virtual ValueTask SetPostLogoutRedirectUrisAsync(TApplication application,
             ImmutableArray<string> addresses, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -806,12 +806,12 @@ namespace OpenIddict.EntityFrameworkCore
         public virtual ValueTask SetPropertiesAsync(TApplication application,
             ImmutableDictionary<string, JsonElement> properties, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
 
-            if (properties == null || properties.IsEmpty)
+            if (properties is null || properties.IsEmpty)
             {
                 application.Properties = null;
 
@@ -831,7 +831,7 @@ namespace OpenIddict.EntityFrameworkCore
         public virtual ValueTask SetRedirectUrisAsync(TApplication application,
             ImmutableArray<string> addresses, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -855,7 +855,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask SetRequirementsAsync(TApplication application, ImmutableArray<string> requirements, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -879,7 +879,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual async ValueTask UpdateAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }

src/OpenIddict.EntityFrameworkCore/Stores/OpenIddictEntityFrameworkCoreAuthorizationStore.cs

@@ -128,7 +128,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual async ValueTask<long> CountAsync<TResult>(Func<IQueryable<TAuthorization>, IQueryable<TResult>> query, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -139,7 +139,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual async ValueTask CreateAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -152,7 +152,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual async ValueTask DeleteAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -437,13 +437,13 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual async ValueTask<string?> GetApplicationIdAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
 
             // If the application is not attached to the authorization, try to load it manually.
-            if (authorization.Application == null)
+            if (authorization.Application is null)
             {
                 var reference = Context.Entry(authorization).Reference(entry => entry.Application);
                 if (reference.EntityEntry.State == EntityState.Detached)
@@ -454,7 +454,7 @@ namespace OpenIddict.EntityFrameworkCore
                 await reference.LoadAsync(cancellationToken);
             }
 
-            if (authorization.Application == null)
+            if (authorization.Application is null)
             {
                 return null;
             }
@@ -467,7 +467,7 @@ namespace OpenIddict.EntityFrameworkCore
             Func<IQueryable<TAuthorization>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -480,7 +480,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<DateTimeOffset?> GetCreationDateAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -491,7 +491,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetIdAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -502,7 +502,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableDictionary<string, JsonElement>> GetPropertiesAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -529,7 +529,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableArray<string>> GetScopesAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -556,7 +556,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetStatusAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -567,7 +567,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetSubjectAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -578,7 +578,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetTypeAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -626,7 +626,7 @@ namespace OpenIddict.EntityFrameworkCore
             Func<IQueryable<TAuthorization>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -713,7 +713,7 @@ namespace OpenIddict.EntityFrameworkCore
                 }
             }
 
-            if (exceptions != null)
+            if (exceptions is not null)
             {
                 throw new AggregateException(SR.GetResourceString(SR.ID1242), exceptions);
             }
@@ -723,7 +723,7 @@ namespace OpenIddict.EntityFrameworkCore
         public virtual async ValueTask SetApplicationIdAsync(TAuthorization authorization,
             string? identifier, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -737,7 +737,7 @@ namespace OpenIddict.EntityFrameworkCore
                 var application = await Applications.AsQueryable()
                     .FirstOrDefaultAsync(application => application.Id!.Equals(key), cancellationToken);
 
-                if (application == null)
+                if (application is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1243));
                 }
@@ -748,7 +748,7 @@ namespace OpenIddict.EntityFrameworkCore
             else
             {
                 // If the application is not attached to the authorization, try to load it manually.
-                if (authorization.Application == null)
+                if (authorization.Application is null)
                 {
                     var reference = Context.Entry(authorization).Reference(entry => entry.Application);
                     if (reference.EntityEntry.State == EntityState.Detached)
@@ -767,7 +767,7 @@ namespace OpenIddict.EntityFrameworkCore
         public virtual ValueTask SetCreationDateAsync(TAuthorization authorization,
             DateTimeOffset? date, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -781,12 +781,12 @@ namespace OpenIddict.EntityFrameworkCore
         public virtual ValueTask SetPropertiesAsync(TAuthorization authorization,
             ImmutableDictionary<string, JsonElement> properties, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
 
-            if (properties == null || properties.IsEmpty)
+            if (properties is null || properties.IsEmpty)
             {
                 authorization.Properties = null;
 
@@ -806,7 +806,7 @@ namespace OpenIddict.EntityFrameworkCore
         public virtual ValueTask SetScopesAsync(TAuthorization authorization,
             ImmutableArray<string> scopes, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -831,7 +831,7 @@ namespace OpenIddict.EntityFrameworkCore
         public virtual ValueTask SetStatusAsync(TAuthorization authorization,
             string? status, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -845,7 +845,7 @@ namespace OpenIddict.EntityFrameworkCore
         public virtual ValueTask SetSubjectAsync(TAuthorization authorization,
             string? subject, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -859,7 +859,7 @@ namespace OpenIddict.EntityFrameworkCore
         public virtual ValueTask SetTypeAsync(TAuthorization authorization,
             string? type, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -872,7 +872,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual async ValueTask UpdateAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }

src/OpenIddict.EntityFrameworkCore/Stores/OpenIddictEntityFrameworkCoreScopeStore.cs

@@ -108,7 +108,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual async ValueTask<long> CountAsync<TResult>(Func<IQueryable<TScope>, IQueryable<TResult>> query, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -119,7 +119,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual async ValueTask CreateAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -132,7 +132,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual async ValueTask DeleteAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -236,7 +236,7 @@ namespace OpenIddict.EntityFrameworkCore
             Func<IQueryable<TScope>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -247,7 +247,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetDescriptionAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -258,7 +258,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableDictionary<CultureInfo, string>> GetDescriptionsAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -286,7 +286,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetDisplayNameAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -297,7 +297,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableDictionary<CultureInfo, string>> GetDisplayNamesAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -325,7 +325,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetIdAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -336,7 +336,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetNameAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -347,7 +347,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableDictionary<string, JsonElement>> GetPropertiesAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -374,7 +374,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableArray<string>> GetResourcesAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -436,7 +436,7 @@ namespace OpenIddict.EntityFrameworkCore
             Func<IQueryable<TScope>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -447,7 +447,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask SetDescriptionAsync(TScope scope, string? description, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -461,12 +461,12 @@ namespace OpenIddict.EntityFrameworkCore
         public virtual ValueTask SetDescriptionsAsync(TScope scope,
             ImmutableDictionary<CultureInfo, string> descriptions, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
 
-            if (descriptions == null || descriptions.IsEmpty)
+            if (descriptions is null || descriptions.IsEmpty)
             {
                 scope.Descriptions = null;
 
@@ -499,7 +499,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask SetDisplayNameAsync(TScope scope, string? name, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -513,12 +513,12 @@ namespace OpenIddict.EntityFrameworkCore
         public virtual ValueTask SetDisplayNamesAsync(TScope scope,
             ImmutableDictionary<CultureInfo, string> names, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
 
-            if (names == null || names.IsEmpty)
+            if (names is null || names.IsEmpty)
             {
                 scope.DisplayNames = null;
 
@@ -551,7 +551,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask SetNameAsync(TScope scope, string? name, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -565,12 +565,12 @@ namespace OpenIddict.EntityFrameworkCore
         public virtual ValueTask SetPropertiesAsync(TScope scope,
             ImmutableDictionary<string, JsonElement> properties, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
 
-            if (properties == null || properties.IsEmpty)
+            if (properties is null || properties.IsEmpty)
             {
                 scope.Properties = null;
 
@@ -589,7 +589,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask SetResourcesAsync(TScope scope, ImmutableArray<string> resources, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -613,7 +613,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual async ValueTask UpdateAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }

src/OpenIddict.EntityFrameworkCore/Stores/OpenIddictEntityFrameworkCoreTokenStore.cs

@@ -128,7 +128,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual async ValueTask<long> CountAsync<TResult>(Func<IQueryable<TToken>, IQueryable<TResult>> query, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -139,7 +139,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual async ValueTask CreateAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -152,7 +152,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual async ValueTask DeleteAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -362,13 +362,13 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual async ValueTask<string?> GetApplicationIdAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
 
             // If the application is not attached to the token, try to load it manually.
-            if (token.Application == null)
+            if (token.Application is null)
             {
                 var reference = Context.Entry(token).Reference(entry => entry.Application);
                 if (reference.EntityEntry.State == EntityState.Detached)
@@ -379,7 +379,7 @@ namespace OpenIddict.EntityFrameworkCore
                 await reference.LoadAsync(cancellationToken);
             }
 
-            if (token.Application == null)
+            if (token.Application is null)
             {
                 return null;
             }
@@ -392,7 +392,7 @@ namespace OpenIddict.EntityFrameworkCore
             Func<IQueryable<TToken>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -406,13 +406,13 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual async ValueTask<string?> GetAuthorizationIdAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
 
             // If the authorization is not attached to the token, try to load it manually.
-            if (token.Authorization == null)
+            if (token.Authorization is null)
             {
                 var reference = Context.Entry(token).Reference(entry => entry.Authorization);
                 if (reference.EntityEntry.State == EntityState.Detached)
@@ -423,7 +423,7 @@ namespace OpenIddict.EntityFrameworkCore
                 await reference.LoadAsync(cancellationToken);
             }
 
-            if (token.Authorization == null)
+            if (token.Authorization is null)
             {
                 return null;
             }
@@ -434,7 +434,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<DateTimeOffset?> GetCreationDateAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -445,7 +445,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<DateTimeOffset?> GetExpirationDateAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -456,7 +456,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetIdAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -467,7 +467,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetPayloadAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -478,7 +478,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableDictionary<string, JsonElement>> GetPropertiesAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -505,7 +505,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetReferenceIdAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -516,7 +516,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetStatusAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -527,7 +527,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetSubjectAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -538,7 +538,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetTypeAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -587,7 +587,7 @@ namespace OpenIddict.EntityFrameworkCore
             Func<IQueryable<TToken>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -674,7 +674,7 @@ namespace OpenIddict.EntityFrameworkCore
                 }
             }
 
-            if (exceptions != null)
+            if (exceptions is not null)
             {
                 throw new AggregateException(SR.GetResourceString(SR.ID1248), exceptions);
             }
@@ -683,7 +683,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual async ValueTask SetApplicationIdAsync(TToken token, string? identifier, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -697,7 +697,7 @@ namespace OpenIddict.EntityFrameworkCore
                 var application = await Applications.AsQueryable()
                     .FirstOrDefaultAsync(application => application.Id!.Equals(key), cancellationToken);
 
-                if (application == null)
+                if (application is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1249));
                 }
@@ -708,7 +708,7 @@ namespace OpenIddict.EntityFrameworkCore
             else
             {
                 // If the application is not attached to the token, try to load it manually.
-                if (token.Application == null)
+                if (token.Application is null)
                 {
                     var reference = Context.Entry(token).Reference(entry => entry.Application);
                     if (reference.EntityEntry.State == EntityState.Detached)
@@ -726,7 +726,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual async ValueTask SetAuthorizationIdAsync(TToken token, string? identifier, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -740,7 +740,7 @@ namespace OpenIddict.EntityFrameworkCore
                 var authorization = await Authorizations.AsQueryable()
                     .FirstOrDefaultAsync(authorization => authorization.Id!.Equals(key), cancellationToken);
 
-                if (authorization == null)
+                if (authorization is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1250));
                 }
@@ -751,7 +751,7 @@ namespace OpenIddict.EntityFrameworkCore
             else
             {
                 // If the authorization is not attached to the token, try to load it manually.
-                if (token.Authorization == null)
+                if (token.Authorization is null)
                 {
                     var reference = Context.Entry(token).Reference(entry => entry.Authorization);
                     if (reference.EntityEntry.State == EntityState.Detached)
@@ -769,7 +769,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask SetCreationDateAsync(TToken token, DateTimeOffset? date, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -782,7 +782,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask SetExpirationDateAsync(TToken token, DateTimeOffset? date, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -795,7 +795,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask SetPayloadAsync(TToken token, string? payload, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -809,12 +809,12 @@ namespace OpenIddict.EntityFrameworkCore
         public virtual ValueTask SetPropertiesAsync(TToken token,
             ImmutableDictionary<string, JsonElement> properties, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
 
-            if (properties == null || properties.IsEmpty)
+            if (properties is null || properties.IsEmpty)
             {
                 token.Properties = null;
 
@@ -833,7 +833,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask SetReferenceIdAsync(TToken token, string? identifier, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -846,7 +846,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask SetStatusAsync(TToken token, string? status, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -859,7 +859,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask SetSubjectAsync(TToken token, string? subject, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -872,7 +872,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual ValueTask SetTypeAsync(TToken token, string? type, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -885,7 +885,7 @@ namespace OpenIddict.EntityFrameworkCore
         /// <inheritdoc/>
         public virtual async ValueTask UpdateAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }

src/OpenIddict.MongoDb/OpenIddictMongoDbBuilder.cs

@@ -40,7 +40,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictMongoDbBuilder"/>.</returns>
         public OpenIddictMongoDbBuilder Configure(Action<OpenIddictMongoDbOptions> configuration)
         {
-            if (configuration == null)
+            if (configuration is null)
             {
                 throw new ArgumentNullException(nameof(configuration));
             }
@@ -166,7 +166,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictMongoDbBuilder"/>.</returns>
         public OpenIddictMongoDbBuilder UseDatabase(IMongoDatabase database)
         {
-            if (database == null)
+            if (database is null)
             {
                 throw new ArgumentNullException(nameof(database));
             }

src/OpenIddict.MongoDb/OpenIddictMongoDbContext.cs

@@ -37,12 +37,12 @@ namespace OpenIddict.MongoDb
             }
 
             var database = _options.CurrentValue.Database;
-            if (database == null)
+            if (database is null)
             {
                 database = _provider.GetService<IMongoDatabase>();
             }
 
-            if (database == null)
+            if (database is null)
             {
                 return new ValueTask<IMongoDatabase>(Task.FromException<IMongoDatabase>(
                     new InvalidOperationException(SR.GetResourceString(SR.ID1261))));

src/OpenIddict.MongoDb/OpenIddictMongoDbExtensions.cs

@@ -25,7 +25,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictMongoDbBuilder"/>.</returns>
         public static OpenIddictMongoDbBuilder UseMongoDb(this OpenIddictCoreBuilder builder)
         {
-            if (builder == null)
+            if (builder is null)
             {
                 throw new ArgumentNullException(nameof(builder));
             }
@@ -67,12 +67,12 @@ namespace Microsoft.Extensions.DependencyInjection
         public static OpenIddictCoreBuilder UseMongoDb(
             this OpenIddictCoreBuilder builder, Action<OpenIddictMongoDbBuilder> configuration)
         {
-            if (builder == null)
+            if (builder is null)
             {
                 throw new ArgumentNullException(nameof(builder));
             }
 
-            if (configuration == null)
+            if (configuration is null)
             {
                 throw new ArgumentNullException(nameof(configuration));
             }

src/OpenIddict.MongoDb/OpenIddictMongoDbHelpers.cs

@@ -26,7 +26,7 @@ namespace MongoDB.Driver
         /// <returns>The streamed async enumeration containing the results.</returns>
         internal static IAsyncEnumerable<T> ToAsyncEnumerable<T>(this IAsyncCursorSource<T> source, CancellationToken cancellationToken)
         {
-            if (source == null)
+            if (source is null)
             {
                 throw new ArgumentNullException(nameof(source));
             }
@@ -56,7 +56,7 @@ namespace MongoDB.Driver
         /// <returns>The streamed async enumeration containing the results.</returns>
         internal static IAsyncEnumerable<T> ToAsyncEnumerable<T>(this IQueryable<T> source, CancellationToken cancellationToken)
         {
-            if (source == null)
+            if (source is null)
             {
                 throw new ArgumentNullException(nameof(source));
             }

src/OpenIddict.MongoDb/Resolvers/OpenIddictMongoDbApplicationStoreResolver.cs

@@ -33,7 +33,7 @@ namespace OpenIddict.MongoDb
         public IOpenIddictApplicationStore<TApplication> Get<TApplication>() where TApplication : class
         {
             var store = _provider.GetService<IOpenIddictApplicationStore<TApplication>>();
-            if (store != null)
+            if (store is not null)
             {
                 return store;
             }

src/OpenIddict.MongoDb/Resolvers/OpenIddictMongoDbAuthorizationStoreResolver.cs

@@ -33,7 +33,7 @@ namespace OpenIddict.MongoDb
         public IOpenIddictAuthorizationStore<TAuthorization> Get<TAuthorization>() where TAuthorization : class
         {
             var store = _provider.GetService<IOpenIddictAuthorizationStore<TAuthorization>>();
-            if (store != null)
+            if (store is not null)
             {
                 return store;
             }

src/OpenIddict.MongoDb/Resolvers/OpenIddictMongoDbScopeStoreResolver.cs

@@ -33,7 +33,7 @@ namespace OpenIddict.MongoDb
         public IOpenIddictScopeStore<TScope> Get<TScope>() where TScope : class
         {
             var store = _provider.GetService<IOpenIddictScopeStore<TScope>>();
-            if (store != null)
+            if (store is not null)
             {
                 return store;
             }

src/OpenIddict.MongoDb/Resolvers/OpenIddictMongoDbTokenStoreResolver.cs

@@ -33,7 +33,7 @@ namespace OpenIddict.MongoDb
         public IOpenIddictTokenStore<TToken> Get<TToken>() where TToken : class
         {
             var store = _provider.GetService<IOpenIddictTokenStore<TToken>>();
-            if (store != null)
+            if (store is not null)
             {
                 return store;
             }

src/OpenIddict.MongoDb/Stores/OpenIddictMongoDbApplicationStore.cs

@@ -62,7 +62,7 @@ namespace OpenIddict.MongoDb
         public virtual async ValueTask<long> CountAsync<TResult>(
             Func<IQueryable<TApplication>, IQueryable<TResult>> query, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -76,7 +76,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual async ValueTask CreateAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -90,7 +90,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual async ValueTask DeleteAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -196,7 +196,7 @@ namespace OpenIddict.MongoDb
             Func<IQueryable<TApplication>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -210,7 +210,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetClientIdAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -221,7 +221,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetClientSecretAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -232,7 +232,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetClientTypeAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -243,7 +243,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetConsentTypeAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -254,7 +254,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetDisplayNameAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -265,12 +265,12 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableDictionary<CultureInfo, string>> GetDisplayNamesAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
 
-            if (application.DisplayNames == null || application.DisplayNames.Count == 0)
+            if (application.DisplayNames is null || application.DisplayNames.Count == 0)
             {
                 return new ValueTask<ImmutableDictionary<CultureInfo, string>>(ImmutableDictionary.Create<CultureInfo, string>());
             }
@@ -281,7 +281,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetIdAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -293,12 +293,12 @@ namespace OpenIddict.MongoDb
         public virtual ValueTask<ImmutableArray<string>> GetPermissionsAsync(
             TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
 
-            if (application.Permissions == null || application.Permissions.Count == 0)
+            if (application.Permissions is null || application.Permissions.Count == 0)
             {
                 return new ValueTask<ImmutableArray<string>>(ImmutableArray.Create<string>());
             }
@@ -310,12 +310,12 @@ namespace OpenIddict.MongoDb
         public virtual ValueTask<ImmutableArray<string>> GetPostLogoutRedirectUrisAsync(
             TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
 
-            if (application.PostLogoutRedirectUris == null || application.PostLogoutRedirectUris.Count == 0)
+            if (application.PostLogoutRedirectUris is null || application.PostLogoutRedirectUris.Count == 0)
             {
                 return new ValueTask<ImmutableArray<string>>(ImmutableArray.Create<string>());
             }
@@ -326,12 +326,12 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableDictionary<string, JsonElement>> GetPropertiesAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
 
-            if (application.Properties == null)
+            if (application.Properties is null)
             {
                 return new ValueTask<ImmutableDictionary<string, JsonElement>>(ImmutableDictionary.Create<string, JsonElement>());
             }
@@ -344,12 +344,12 @@ namespace OpenIddict.MongoDb
         public virtual ValueTask<ImmutableArray<string>> GetRedirectUrisAsync(
             TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
 
-            if (application.RedirectUris == null || application.RedirectUris.Count == 0)
+            if (application.RedirectUris is null || application.RedirectUris.Count == 0)
             {
                 return new ValueTask<ImmutableArray<string>>(ImmutableArray.Create<string>());
             }
@@ -360,12 +360,12 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableArray<string>> GetRequirementsAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
 
-            if (application.Requirements == null || application.Requirements.Count == 0)
+            if (application.Requirements is null || application.Requirements.Count == 0)
             {
                 return new ValueTask<ImmutableArray<string>>(ImmutableArray.Create<string>());
             }
@@ -418,7 +418,7 @@ namespace OpenIddict.MongoDb
             Func<IQueryable<TApplication>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -441,7 +441,7 @@ namespace OpenIddict.MongoDb
         public virtual ValueTask SetClientIdAsync(TApplication application,
             string? identifier, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -455,7 +455,7 @@ namespace OpenIddict.MongoDb
         public virtual ValueTask SetClientSecretAsync(TApplication application,
             string? secret, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -469,7 +469,7 @@ namespace OpenIddict.MongoDb
         public virtual ValueTask SetClientTypeAsync(TApplication application,
             string? type, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -483,7 +483,7 @@ namespace OpenIddict.MongoDb
         public virtual ValueTask SetConsentTypeAsync(TApplication application,
             string? type, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -497,7 +497,7 @@ namespace OpenIddict.MongoDb
         public virtual ValueTask SetDisplayNameAsync(TApplication application,
             string? name, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -511,7 +511,7 @@ namespace OpenIddict.MongoDb
         public virtual ValueTask SetDisplayNamesAsync(TApplication application,
             ImmutableDictionary<CultureInfo, string> names, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -524,7 +524,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask SetPermissionsAsync(TApplication application, ImmutableArray<string> permissions, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -545,7 +545,7 @@ namespace OpenIddict.MongoDb
         public virtual ValueTask SetPostLogoutRedirectUrisAsync(TApplication application,
             ImmutableArray<string> addresses, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -566,12 +566,12 @@ namespace OpenIddict.MongoDb
         public virtual ValueTask SetPropertiesAsync(TApplication application,
             ImmutableDictionary<string, JsonElement> properties, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
 
-            if (properties == null || properties.IsEmpty)
+            if (properties is null || properties.IsEmpty)
             {
                 application.Properties = null;
 
@@ -591,7 +591,7 @@ namespace OpenIddict.MongoDb
         public virtual ValueTask SetRedirectUrisAsync(TApplication application,
             ImmutableArray<string> addresses, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -612,7 +612,7 @@ namespace OpenIddict.MongoDb
         public virtual ValueTask SetRequirementsAsync(TApplication application,
             ImmutableArray<string> requirements, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }
@@ -632,7 +632,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual async ValueTask UpdateAsync(TApplication application, CancellationToken cancellationToken)
         {
-            if (application == null)
+            if (application is null)
             {
                 throw new ArgumentNullException(nameof(application));
             }

src/OpenIddict.MongoDb/Stores/OpenIddictMongoDbAuthorizationStore.cs

@@ -61,7 +61,7 @@ namespace OpenIddict.MongoDb
         public virtual async ValueTask<long> CountAsync<TResult>(
             Func<IQueryable<TAuthorization>, IQueryable<TResult>> query, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -75,7 +75,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual async ValueTask CreateAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -89,7 +89,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual async ValueTask DeleteAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -332,7 +332,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetApplicationIdAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -350,7 +350,7 @@ namespace OpenIddict.MongoDb
             Func<IQueryable<TAuthorization>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -364,7 +364,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<DateTimeOffset?> GetCreationDateAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -375,7 +375,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetIdAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -386,12 +386,12 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableDictionary<string, JsonElement>> GetPropertiesAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
 
-            if (authorization.Properties == null)
+            if (authorization.Properties is null)
             {
                 return new ValueTask<ImmutableDictionary<string, JsonElement>>(ImmutableDictionary.Create<string, JsonElement>());
             }
@@ -403,12 +403,12 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableArray<string>> GetScopesAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
 
-            if (authorization.Scopes == null || authorization.Scopes.Count == 0)
+            if (authorization.Scopes is null || authorization.Scopes.Count == 0)
             {
                 return new ValueTask<ImmutableArray<string>>(ImmutableArray.Create<string>());
             }
@@ -419,7 +419,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetStatusAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -430,7 +430,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetSubjectAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -441,7 +441,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetTypeAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -494,7 +494,7 @@ namespace OpenIddict.MongoDb
             Func<IQueryable<TAuthorization>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -556,7 +556,7 @@ namespace OpenIddict.MongoDb
                     }
                 }
 
-                if (buffer != null)
+                if (buffer is not null)
                 {
                     yield return buffer;
                 }
@@ -567,7 +567,7 @@ namespace OpenIddict.MongoDb
         public virtual ValueTask SetApplicationIdAsync(TAuthorization authorization,
             string? identifier, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -589,7 +589,7 @@ namespace OpenIddict.MongoDb
         public virtual ValueTask SetCreationDateAsync(TAuthorization authorization,
             DateTimeOffset? date, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -603,12 +603,12 @@ namespace OpenIddict.MongoDb
         public virtual ValueTask SetPropertiesAsync(TAuthorization authorization,
             ImmutableDictionary<string, JsonElement> properties, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
 
-            if (properties == null || properties.IsEmpty)
+            if (properties is null || properties.IsEmpty)
             {
                 authorization.Properties = null;
 
@@ -628,7 +628,7 @@ namespace OpenIddict.MongoDb
         public virtual ValueTask SetScopesAsync(TAuthorization authorization,
             ImmutableArray<string> scopes, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -648,7 +648,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask SetStatusAsync(TAuthorization authorization, string? status, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -661,7 +661,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask SetSubjectAsync(TAuthorization authorization, string? subject, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -674,7 +674,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask SetTypeAsync(TAuthorization authorization, string? type, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }
@@ -687,7 +687,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual async ValueTask UpdateAsync(TAuthorization authorization, CancellationToken cancellationToken)
         {
-            if (authorization == null)
+            if (authorization is null)
             {
                 throw new ArgumentNullException(nameof(authorization));
             }

src/OpenIddict.MongoDb/Stores/OpenIddictMongoDbScopeStore.cs

@@ -62,7 +62,7 @@ namespace OpenIddict.MongoDb
         public virtual async ValueTask<long> CountAsync<TResult>(
             Func<IQueryable<TScope>, IQueryable<TResult>> query, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -76,7 +76,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual async ValueTask CreateAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -90,7 +90,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual async ValueTask DeleteAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -185,7 +185,7 @@ namespace OpenIddict.MongoDb
             Func<IQueryable<TScope>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -199,7 +199,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetDescriptionAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -210,12 +210,12 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableDictionary<CultureInfo, string>> GetDescriptionsAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
 
-            if (scope.Descriptions == null || scope.Descriptions.Count == 0)
+            if (scope.Descriptions is null || scope.Descriptions.Count == 0)
             {
                 return new ValueTask<ImmutableDictionary<CultureInfo, string>>(ImmutableDictionary.Create<CultureInfo, string>());
             }
@@ -226,7 +226,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetDisplayNameAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -237,12 +237,12 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableDictionary<CultureInfo, string>> GetDisplayNamesAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
 
-            if (scope.DisplayNames == null || scope.DisplayNames.Count == 0)
+            if (scope.DisplayNames is null || scope.DisplayNames.Count == 0)
             {
                 return new ValueTask<ImmutableDictionary<CultureInfo, string>>(ImmutableDictionary.Create<CultureInfo, string>());
             }
@@ -253,7 +253,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetIdAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -264,7 +264,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetNameAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -275,12 +275,12 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableDictionary<string, JsonElement>> GetPropertiesAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
 
-            if (scope.Properties == null)
+            if (scope.Properties is null)
             {
                 return new ValueTask<ImmutableDictionary<string, JsonElement>>(ImmutableDictionary.Create<string, JsonElement>());
             }
@@ -292,12 +292,12 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableArray<string>> GetResourcesAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
 
-            if (scope.Resources == null || scope.Resources.Count == 0)
+            if (scope.Resources is null || scope.Resources.Count == 0)
             {
                 return new ValueTask<ImmutableArray<string>>(ImmutableArray.Create<string>());
             }
@@ -350,7 +350,7 @@ namespace OpenIddict.MongoDb
             Func<IQueryable<TScope>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -372,7 +372,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask SetDescriptionAsync(TScope scope, string? description, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -386,7 +386,7 @@ namespace OpenIddict.MongoDb
         public virtual ValueTask SetDescriptionsAsync(TScope scope,
             ImmutableDictionary<CultureInfo, string> descriptions, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -400,7 +400,7 @@ namespace OpenIddict.MongoDb
         public virtual ValueTask SetDisplayNamesAsync(TScope scope,
             ImmutableDictionary<CultureInfo, string> names, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -413,7 +413,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask SetDisplayNameAsync(TScope scope, string? name, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -426,7 +426,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask SetNameAsync(TScope scope, string? name, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -440,12 +440,12 @@ namespace OpenIddict.MongoDb
         public virtual ValueTask SetPropertiesAsync(TScope scope,
             ImmutableDictionary<string, JsonElement> properties, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
 
-            if (properties == null || properties.IsEmpty)
+            if (properties is null || properties.IsEmpty)
             {
                 scope.Properties = null;
 
@@ -464,7 +464,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask SetResourcesAsync(TScope scope, ImmutableArray<string> resources, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }
@@ -484,7 +484,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual async ValueTask UpdateAsync(TScope scope, CancellationToken cancellationToken)
         {
-            if (scope == null)
+            if (scope is null)
             {
                 throw new ArgumentNullException(nameof(scope));
             }

src/OpenIddict.MongoDb/Stores/OpenIddictMongoDbTokenStore.cs

@@ -62,7 +62,7 @@ namespace OpenIddict.MongoDb
         public virtual async ValueTask<long> CountAsync<TResult>(
             Func<IQueryable<TToken>, IQueryable<TResult>> query, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -76,7 +76,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual async ValueTask CreateAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -90,7 +90,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual async ValueTask DeleteAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -315,7 +315,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetApplicationIdAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -333,7 +333,7 @@ namespace OpenIddict.MongoDb
             Func<IQueryable<TToken>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -347,7 +347,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetAuthorizationIdAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -363,7 +363,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<DateTimeOffset?> GetCreationDateAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -374,7 +374,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<DateTimeOffset?> GetExpirationDateAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -385,7 +385,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetIdAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -396,7 +396,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetPayloadAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -407,12 +407,12 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<ImmutableDictionary<string, JsonElement>> GetPropertiesAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
 
-            if (token.Properties == null)
+            if (token.Properties is null)
             {
                 return new ValueTask<ImmutableDictionary<string, JsonElement>>(ImmutableDictionary.Create<string, JsonElement>());
             }
@@ -424,7 +424,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetReferenceIdAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -435,7 +435,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetStatusAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -446,7 +446,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetSubjectAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -457,7 +457,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask<string?> GetTypeAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -510,7 +510,7 @@ namespace OpenIddict.MongoDb
             Func<IQueryable<TToken>, TState, IQueryable<TResult>> query,
             TState state, CancellationToken cancellationToken)
         {
-            if (query == null)
+            if (query is null)
             {
                 throw new ArgumentNullException(nameof(query));
             }
@@ -573,7 +573,7 @@ namespace OpenIddict.MongoDb
                     }
                 }
 
-                if (buffer != null)
+                if (buffer is not null)
                 {
                     yield return buffer;
                 }
@@ -583,7 +583,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask SetApplicationIdAsync(TToken token, string? identifier, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -604,7 +604,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask SetAuthorizationIdAsync(TToken token, string? identifier, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -625,7 +625,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask SetCreationDateAsync(TToken token, DateTimeOffset? date, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -638,7 +638,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask SetExpirationDateAsync(TToken token, DateTimeOffset? date, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -651,7 +651,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask SetPayloadAsync(TToken token, string? payload, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -665,12 +665,12 @@ namespace OpenIddict.MongoDb
         public virtual ValueTask SetPropertiesAsync(TToken token,
             ImmutableDictionary<string, JsonElement> properties, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
 
-            if (properties == null || properties.IsEmpty)
+            if (properties is null || properties.IsEmpty)
             {
                 token.Properties = null;
 
@@ -689,7 +689,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask SetReferenceIdAsync(TToken token, string? identifier, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -702,7 +702,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask SetStatusAsync(TToken token, string? status, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -715,7 +715,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask SetSubjectAsync(TToken token, string? subject, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -728,7 +728,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual ValueTask SetTypeAsync(TToken token, string? type, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }
@@ -741,7 +741,7 @@ namespace OpenIddict.MongoDb
         /// <inheritdoc/>
         public virtual async ValueTask UpdateAsync(TToken token, CancellationToken cancellationToken)
         {
-            if (token == null)
+            if (token is null)
             {
                 throw new ArgumentNullException(nameof(token));
             }

src/OpenIddict.Server.AspNetCore/OpenIddictServerAspNetCoreBuilder.cs

@@ -41,7 +41,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerAspNetCoreBuilder"/>.</returns>
         public OpenIddictServerAspNetCoreBuilder Configure(Action<OpenIddictServerAspNetCoreOptions> configuration)
         {
-            if (configuration == null)
+            if (configuration is null)
             {
                 throw new ArgumentNullException(nameof(configuration));
             }
@@ -172,7 +172,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerAspNetCoreBuilder"/>.</returns>
         public OpenIddictServerAspNetCoreBuilder SetAuthorizationEndpointCachingPolicy(DistributedCacheEntryOptions policy)
         {
-            if (policy == null)
+            if (policy is null)
             {
                 throw new ArgumentNullException(nameof(policy));
             }
@@ -188,7 +188,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerAspNetCoreBuilder"/>.</returns>
         public OpenIddictServerAspNetCoreBuilder SetLogoutEndpointCachingPolicy(DistributedCacheEntryOptions policy)
         {
-            if (policy == null)
+            if (policy is null)
             {
                 throw new ArgumentNullException(nameof(policy));
             }

src/OpenIddict.Server.AspNetCore/OpenIddictServerAspNetCoreConfiguration.cs

@@ -26,7 +26,7 @@ namespace OpenIddict.Server.AspNetCore
         /// <param name="options">The options instance to initialize.</param>
         public void Configure(AuthenticationOptions options)
         {
-            if (options == null)
+            if (options is null)
             {
                 throw new ArgumentNullException(nameof(options));
             }
@@ -44,7 +44,7 @@ namespace OpenIddict.Server.AspNetCore
 
         public void Configure(OpenIddictServerOptions options)
         {
-            if (options == null)
+            if (options is null)
             {
                 throw new ArgumentNullException(nameof(options));
             }
@@ -60,7 +60,7 @@ namespace OpenIddict.Server.AspNetCore
         /// <param name="options">The options instance to initialize.</param>
         public void PostConfigure(string name, AuthenticationOptions options)
         {
-            if (options == null)
+            if (options is null)
             {
                 throw new ArgumentNullException(nameof(options));
             }
@@ -95,7 +95,7 @@ namespace OpenIddict.Server.AspNetCore
         /// <param name="options">The options instance to initialize.</param>
         public void PostConfigure(string name, OpenIddictServerAspNetCoreOptions options)
         {
-            if (options == null)
+            if (options is null)
             {
                 throw new ArgumentNullException(nameof(options));
             }

src/OpenIddict.Server.AspNetCore/OpenIddictServerAspNetCoreExtensions.cs

@@ -29,7 +29,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerAspNetCoreBuilder"/>.</returns>
         public static OpenIddictServerAspNetCoreBuilder UseAspNetCore(this OpenIddictServerBuilder builder)
         {
-            if (builder == null)
+            if (builder is null)
             {
                 throw new ArgumentNullException(nameof(builder));
             }
@@ -80,12 +80,12 @@ namespace Microsoft.Extensions.DependencyInjection
         public static OpenIddictServerBuilder UseAspNetCore(
             this OpenIddictServerBuilder builder, Action<OpenIddictServerAspNetCoreBuilder> configuration)
         {
-            if (builder == null)
+            if (builder is null)
             {
                 throw new ArgumentNullException(nameof(builder));
             }
 
-            if (configuration == null)
+            if (configuration is null)
             {
                 throw new ArgumentNullException(nameof(configuration));
             }

src/OpenIddict.Server.AspNetCore/OpenIddictServerAspNetCoreHandler.cs

@@ -54,7 +54,7 @@ namespace OpenIddict.Server.AspNetCore
             // Note: the transaction may be already attached when replaying an ASP.NET Core request
             // (e.g when using the built-in status code pages middleware with the re-execute mode).
             var transaction = Context.Features.Get<OpenIddictServerAspNetCoreFeature>()?.Transaction;
-            if (transaction == null)
+            if (transaction is null)
             {
                 // Create a new transaction and attach the HTTP request to make it available to the ASP.NET Core handlers.
                 transaction = await _factory.CreateTransactionAsync();
@@ -118,7 +118,7 @@ namespace OpenIddict.Server.AspNetCore
             // (generally later in the pipeline, when using the pass-through mode). To avoid having to re-validate it,
             // the authentication context is resolved from the transaction. If it's not available, a new one is created.
             var context = transaction.GetProperty<ProcessAuthenticationContext>(typeof(ProcessAuthenticationContext).FullName!);
-            if (context == null)
+            if (context is null)
             {
                 context = new ProcessAuthenticationContext(transaction);
                 await _dispatcher.DispatchAsync(context);
@@ -155,7 +155,7 @@ namespace OpenIddict.Server.AspNetCore
 
             else
             {
-                Debug.Assert(context.Principal != null, SR.GetResourceString(SR.ID5006));
+                Debug.Assert(context.Principal is not null, SR.GetResourceString(SR.ID5006));
                 Debug.Assert(!string.IsNullOrEmpty(context.Principal.GetTokenType()), SR.GetResourceString(SR.ID5009));
                 Debug.Assert(!string.IsNullOrEmpty(context.Token), SR.GetResourceString(SR.ID5010));
 
@@ -227,7 +227,7 @@ namespace OpenIddict.Server.AspNetCore
         /// <inheritdoc/>
         public async Task SignInAsync(ClaimsPrincipal user, AuthenticationProperties? properties)
         {
-            if (user == null)
+            if (user is null)
             {
                 throw new ArgumentNullException(nameof(user));
             }

src/OpenIddict.Server.AspNetCore/OpenIddictServerAspNetCoreHandlerFilters.cs

@@ -31,7 +31,7 @@ namespace OpenIddict.Server.AspNetCore
 
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -53,7 +53,7 @@ namespace OpenIddict.Server.AspNetCore
 
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -74,7 +74,7 @@ namespace OpenIddict.Server.AspNetCore
 
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -90,12 +90,12 @@ namespace OpenIddict.Server.AspNetCore
         {
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
 
-                return new ValueTask<bool>(context.Transaction.GetHttpRequest() != null);
+                return new ValueTask<bool>(context.Transaction.GetHttpRequest() is not null);
             }
         }
 
@@ -111,7 +111,7 @@ namespace OpenIddict.Server.AspNetCore
 
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -133,7 +133,7 @@ namespace OpenIddict.Server.AspNetCore
 
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -154,7 +154,7 @@ namespace OpenIddict.Server.AspNetCore
 
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -175,7 +175,7 @@ namespace OpenIddict.Server.AspNetCore
 
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -197,7 +197,7 @@ namespace OpenIddict.Server.AspNetCore
 
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -219,7 +219,7 @@ namespace OpenIddict.Server.AspNetCore
 
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -241,7 +241,7 @@ namespace OpenIddict.Server.AspNetCore
 
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }

src/OpenIddict.Server.AspNetCore/OpenIddictServerAspNetCoreHandlers.Authentication.cs

@@ -90,12 +90,12 @@ namespace OpenIddict.Server.AspNetCore
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ExtractAuthorizationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
 
-                    Debug.Assert(context.Request != null, SR.GetResourceString(SR.ID5008));
+                    Debug.Assert(context.Request is not null, SR.GetResourceString(SR.ID5008));
 
                     // If a request_id parameter can be found in the authorization request,
                     // restore the complete authorization request from the distributed cache.
@@ -108,7 +108,7 @@ namespace OpenIddict.Server.AspNetCore
                     // Note: the cache key is always prefixed with a specific marker
                     // to avoid collisions with the other types of cached payloads.
                     var token = await _cache.GetStringAsync(Cache.AuthorizationRequest + context.Request.RequestId);
-                    if (token == null || !context.Options.JsonWebTokenHandler.CanReadToken(token))
+                    if (token is null || !context.Options.JsonWebTokenHandler.CanReadToken(token))
                     {
                         context.Logger.LogError(SR.GetResourceString(SR.ID7146), Parameters.RequestId);
 
@@ -191,17 +191,17 @@ namespace OpenIddict.Server.AspNetCore
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ExtractAuthorizationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
 
-                    Debug.Assert(context.Request != null, SR.GetResourceString(SR.ID5008));
+                    Debug.Assert(context.Request is not null, SR.GetResourceString(SR.ID5008));
 
                     // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
                     // this may indicate that the request was incorrectly processed by another server stack.
                     var request = context.Transaction.GetHttpRequest();
-                    if (request == null)
+                    if (request is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1113));
                     }
@@ -295,7 +295,7 @@ namespace OpenIddict.Server.AspNetCore
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(ApplyAuthorizationResponseContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -340,7 +340,7 @@ namespace OpenIddict.Server.AspNetCore
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ApplyAuthorizationResponseContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -348,7 +348,7 @@ namespace OpenIddict.Server.AspNetCore
                     // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
                     // this may indicate that the request was incorrectly processed by another server stack.
                     var response = context.Transaction.GetHttpRequest()?.HttpContext.Response;
-                    if (response == null)
+                    if (response is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1113));
                     }
@@ -379,7 +379,7 @@ namespace OpenIddict.Server.AspNetCore
                         foreach (var (key, value) in
                             from parameter in context.Response.GetParameters()
                             let values = (string?[]?) parameter.Value
-                            where values != null
+                            where values is not null
                             from value in values
                             where !string.IsNullOrEmpty(value)
                             select (parameter.Key, Value: value))
@@ -430,7 +430,7 @@ namespace OpenIddict.Server.AspNetCore
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(ApplyAuthorizationResponseContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -438,7 +438,7 @@ namespace OpenIddict.Server.AspNetCore
                     // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
                     // this may indicate that the request was incorrectly processed by another server stack.
                     var response = context.Transaction.GetHttpRequest()?.HttpContext.Response;
-                    if (response == null)
+                    if (response is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1113));
                     }
@@ -459,7 +459,7 @@ namespace OpenIddict.Server.AspNetCore
                     foreach (var (key, value) in
                         from parameter in context.Response.GetParameters()
                         let values = (string?[]?) parameter.Value
-                        where values != null
+                        where values is not null
                         from value in values
                         where !string.IsNullOrEmpty(value)
                         select (parameter.Key, Value: value))
@@ -494,7 +494,7 @@ namespace OpenIddict.Server.AspNetCore
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(ApplyAuthorizationResponseContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -502,7 +502,7 @@ namespace OpenIddict.Server.AspNetCore
                     // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
                     // this may indicate that the request was incorrectly processed by another server stack.
                     var response = context.Transaction.GetHttpRequest()?.HttpContext.Response;
-                    if (response == null)
+                    if (response is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1113));
                     }
@@ -523,7 +523,7 @@ namespace OpenIddict.Server.AspNetCore
                     foreach (var (key, value) in
                         from parameter in context.Response.GetParameters()
                         let values = (string?[]?) parameter.Value
-                        where values != null
+                        where values is not null
                         from value in values
                         where !string.IsNullOrEmpty(value)
                         select (parameter.Key, Value: value))

src/OpenIddict.Server.AspNetCore/OpenIddictServerAspNetCoreHandlers.Session.cs

@@ -87,12 +87,12 @@ namespace OpenIddict.Server.AspNetCore
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ExtractLogoutRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
 
-                    Debug.Assert(context.Request != null, SR.GetResourceString(SR.ID5008));
+                    Debug.Assert(context.Request is not null, SR.GetResourceString(SR.ID5008));
 
                     // If a request_id parameter can be found in the logout request,
                     // restore the complete logout request from the distributed cache.
@@ -105,7 +105,7 @@ namespace OpenIddict.Server.AspNetCore
                     // Note: the cache key is always prefixed with a specific marker
                     // to avoid collisions with the other types of cached payloads.
                     var token = await _cache.GetStringAsync(Cache.LogoutRequest + context.Request.RequestId);
-                    if (token == null || !context.Options.JsonWebTokenHandler.CanReadToken(token))
+                    if (token is null || !context.Options.JsonWebTokenHandler.CanReadToken(token))
                     {
                         context.Logger.LogError(SR.GetResourceString(SR.ID7150), Parameters.RequestId);
 
@@ -188,17 +188,17 @@ namespace OpenIddict.Server.AspNetCore
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ExtractLogoutRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
 
-                    Debug.Assert(context.Request != null, SR.GetResourceString(SR.ID5008));
+                    Debug.Assert(context.Request is not null, SR.GetResourceString(SR.ID5008));
 
                     // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
                     // this may indicate that the request was incorrectly processed by another server stack.
                     var request = context.Transaction.GetHttpRequest();
-                    if (request == null)
+                    if (request is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1113));
                     }
@@ -292,7 +292,7 @@ namespace OpenIddict.Server.AspNetCore
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(ApplyLogoutResponseContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -332,7 +332,7 @@ namespace OpenIddict.Server.AspNetCore
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(ApplyLogoutResponseContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -340,7 +340,7 @@ namespace OpenIddict.Server.AspNetCore
                     // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
                     // this may indicate that the request was incorrectly processed by another server stack.
                     var response = context.Transaction.GetHttpRequest()?.HttpContext.Response;
-                    if (response == null)
+                    if (response is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1113));
                     }
@@ -360,7 +360,7 @@ namespace OpenIddict.Server.AspNetCore
                     foreach (var (key, value) in
                         from parameter in context.Response.GetParameters()
                         let values = (string?[]?) parameter.Value
-                        where values != null
+                        where values is not null
                         from value in values
                         where !string.IsNullOrEmpty(value)
                         select (parameter.Key, Value: value))

src/OpenIddict.Server.AspNetCore/OpenIddictServerAspNetCoreHandlers.cs

@@ -87,7 +87,7 @@ namespace OpenIddict.Server.AspNetCore
             /// <inheritdoc/>
             public ValueTask HandleAsync(ProcessRequestContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -95,7 +95,7 @@ namespace OpenIddict.Server.AspNetCore
                 // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var request = context.Transaction.GetHttpRequest();
-                if (request == null)
+                if (request is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1113));
                 }
@@ -189,7 +189,7 @@ namespace OpenIddict.Server.AspNetCore
             /// <inheritdoc/>
             public ValueTask HandleAsync(ProcessRequestContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -197,14 +197,14 @@ namespace OpenIddict.Server.AspNetCore
                 // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var request = context.Transaction.GetHttpRequest();
-                if (request == null)
+                if (request is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1113));
                 }
 
                 // Don't require that the request host be present if the request is not handled
                 // by an OpenIddict endpoint or if an explicit issuer URL was already set.
-                if (context.Issuer != null || context.EndpointType == OpenIddictServerEndpointType.Unknown)
+                if (context.Issuer is not null || context.EndpointType == OpenIddictServerEndpointType.Unknown)
                 {
                     return default;
                 }
@@ -255,7 +255,7 @@ namespace OpenIddict.Server.AspNetCore
             /// <inheritdoc/>
             public ValueTask HandleAsync(ProcessRequestContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -263,7 +263,7 @@ namespace OpenIddict.Server.AspNetCore
                 // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var request = context.Transaction.GetHttpRequest();
-                if (request == null)
+                if (request is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1113));
                 }
@@ -308,13 +308,13 @@ namespace OpenIddict.Server.AspNetCore
             /// <inheritdoc/>
             public ValueTask HandleAsync(ProcessChallengeContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
 
                 var properties = context.Transaction.GetProperty<AuthenticationProperties>(typeof(AuthenticationProperties).FullName!);
-                if (properties != null)
+                if (properties is not null)
                 {
                     context.Response.Error = properties.GetString(Properties.Error);
                     context.Response.ErrorDescription = properties.GetString(Properties.ErrorDescription);
@@ -346,15 +346,15 @@ namespace OpenIddict.Server.AspNetCore
             /// <inheritdoc/>
             public ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
 
-                Debug.Assert(context.Transaction.Response != null, SR.GetResourceString(SR.ID5007));
+                Debug.Assert(context.Transaction.Response is not null, SR.GetResourceString(SR.ID5007));
 
                 var properties = context.Transaction.GetProperty<AuthenticationProperties>(typeof(AuthenticationProperties).FullName!);
-                if (properties == null)
+                if (properties is null)
                 {
                     return default;
                 }
@@ -400,7 +400,7 @@ namespace OpenIddict.Server.AspNetCore
             /// <inheritdoc/>
             public ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -408,7 +408,7 @@ namespace OpenIddict.Server.AspNetCore
                 // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var request = context.Transaction.GetHttpRequest();
-                if (request == null)
+                if (request is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1113));
                 }
@@ -453,7 +453,7 @@ namespace OpenIddict.Server.AspNetCore
             /// <inheritdoc/>
             public async ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -461,7 +461,7 @@ namespace OpenIddict.Server.AspNetCore
                 // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var request = context.Transaction.GetHttpRequest();
-                if (request == null)
+                if (request is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1113));
                 }
@@ -533,7 +533,7 @@ namespace OpenIddict.Server.AspNetCore
             /// <inheritdoc/>
             public async ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -541,7 +541,7 @@ namespace OpenIddict.Server.AspNetCore
                 // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var request = context.Transaction.GetHttpRequest();
-                if (request == null)
+                if (request is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1113));
                 }
@@ -609,17 +609,17 @@ namespace OpenIddict.Server.AspNetCore
             /// <inheritdoc/>
             public ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
 
-                Debug.Assert(context.Transaction.Request != null, SR.GetResourceString(SR.ID5008));
+                Debug.Assert(context.Transaction.Request is not null, SR.GetResourceString(SR.ID5008));
 
                 // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var request = context.Transaction.GetHttpRequest();
-                if (request == null)
+                if (request is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1113));
                 }
@@ -708,7 +708,7 @@ namespace OpenIddict.Server.AspNetCore
             /// <inheritdoc/>
             public ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -716,12 +716,12 @@ namespace OpenIddict.Server.AspNetCore
                 // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var request = context.Transaction.GetHttpRequest();
-                if (request == null)
+                if (request is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1113));
                 }
 
-                Debug.Assert(context.Transaction.Request != null, SR.GetResourceString(SR.ID5008));
+                Debug.Assert(context.Transaction.Request is not null, SR.GetResourceString(SR.ID5008));
 
                 string header = request.Headers[HeaderNames.Authorization];
                 if (string.IsNullOrEmpty(header) || !header.StartsWith("Bearer ", StringComparison.OrdinalIgnoreCase))
@@ -759,7 +759,7 @@ namespace OpenIddict.Server.AspNetCore
             /// <inheritdoc/>
             public ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -790,7 +790,7 @@ namespace OpenIddict.Server.AspNetCore
             /// <inheritdoc/>
             public ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -798,12 +798,12 @@ namespace OpenIddict.Server.AspNetCore
                 // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var response = context.Transaction.GetHttpRequest()?.HttpContext.Response;
-                if (response == null)
+                if (response is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1113));
                 }
 
-                Debug.Assert(context.Transaction.Response != null, SR.GetResourceString(SR.ID5007));
+                Debug.Assert(context.Transaction.Response is not null, SR.GetResourceString(SR.ID5007));
 
                 // When client authentication is made using basic authentication, the authorization server MUST return
                 // a 401 response with a valid WWW-Authenticate header containing the Basic scheme and a non-empty realm.
@@ -850,7 +850,7 @@ namespace OpenIddict.Server.AspNetCore
             /// <inheritdoc/>
             public ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -858,7 +858,7 @@ namespace OpenIddict.Server.AspNetCore
                 // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var response = context.Transaction.GetHttpRequest()?.HttpContext.Response;
-                if (response == null)
+                if (response is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1113));
                 }
@@ -897,7 +897,7 @@ namespace OpenIddict.Server.AspNetCore
             /// <inheritdoc/>
             public ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -905,12 +905,12 @@ namespace OpenIddict.Server.AspNetCore
                 // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var response = context.Transaction.GetHttpRequest()?.HttpContext.Response;
-                if (response == null)
+                if (response is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1113));
                 }
 
-                Debug.Assert(context.Transaction.Response != null, SR.GetResourceString(SR.ID5007));
+                Debug.Assert(context.Transaction.Response is not null, SR.GetResourceString(SR.ID5007));
 
                 // When client authentication is made using basic authentication, the authorization server MUST return
                 // a 401 response with a valid WWW-Authenticate header containing the HTTP Basic authentication scheme.
@@ -1011,7 +1011,7 @@ namespace OpenIddict.Server.AspNetCore
             /// <inheritdoc/>
             public ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -1019,7 +1019,7 @@ namespace OpenIddict.Server.AspNetCore
                 // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var response = context.Transaction.GetHttpRequest()?.HttpContext.Response;
-                if (response == null)
+                if (response is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1113));
                 }
@@ -1057,7 +1057,7 @@ namespace OpenIddict.Server.AspNetCore
             /// <inheritdoc/>
             public async ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -1065,7 +1065,7 @@ namespace OpenIddict.Server.AspNetCore
                 // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var response = context.Transaction.GetHttpRequest()?.HttpContext.Response;
-                if (response == null)
+                if (response is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1113));
                 }
@@ -1114,7 +1114,7 @@ namespace OpenIddict.Server.AspNetCore
             /// <inheritdoc/>
             public ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -1122,12 +1122,12 @@ namespace OpenIddict.Server.AspNetCore
                 // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var response = context.Transaction.GetHttpRequest()?.HttpContext.Response;
-                if (response == null)
+                if (response is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1113));
                 }
 
-                Debug.Assert(context.Transaction.Response != null, SR.GetResourceString(SR.ID5007));
+                Debug.Assert(context.Transaction.Response is not null, SR.GetResourceString(SR.ID5007));
 
                 if (string.IsNullOrEmpty(context.Transaction.Response.Error))
                 {
@@ -1162,7 +1162,7 @@ namespace OpenIddict.Server.AspNetCore
             /// <inheritdoc/>
             public ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -1170,12 +1170,12 @@ namespace OpenIddict.Server.AspNetCore
                 // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var response = context.Transaction.GetHttpRequest()?.HttpContext.Response;
-                if (response == null)
+                if (response is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1113));
                 }
 
-                Debug.Assert(context.Transaction.Response != null, SR.GetResourceString(SR.ID5007));
+                Debug.Assert(context.Transaction.Response is not null, SR.GetResourceString(SR.ID5007));
 
                 if (string.IsNullOrEmpty(context.Transaction.Response.Error))
                 {
@@ -1186,7 +1186,7 @@ namespace OpenIddict.Server.AspNetCore
                 // If it was not registered or enabled, let the default OpenIddict server handlers render
                 // a default error page instead of delegating the rendering to the status code middleware.
                 var feature = response.HttpContext.Features.Get<IStatusCodePagesFeature>();
-                if (feature == null || !feature.Enabled)
+                if (feature is null || !feature.Enabled)
                 {
                     return default;
                 }
@@ -1221,7 +1221,7 @@ namespace OpenIddict.Server.AspNetCore
             /// <inheritdoc/>
             public async ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -1229,12 +1229,12 @@ namespace OpenIddict.Server.AspNetCore
                 // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var response = context.Transaction.GetHttpRequest()?.HttpContext.Response;
-                if (response == null)
+                if (response is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1113));
                 }
 
-                Debug.Assert(context.Transaction.Response != null, SR.GetResourceString(SR.ID5007));
+                Debug.Assert(context.Transaction.Response is not null, SR.GetResourceString(SR.ID5007));
 
                 if (string.IsNullOrEmpty(context.Transaction.Response.Error))
                 {
@@ -1298,7 +1298,7 @@ namespace OpenIddict.Server.AspNetCore
             /// <inheritdoc/>
             public ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -1306,13 +1306,13 @@ namespace OpenIddict.Server.AspNetCore
                 // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var response = context.Transaction.GetHttpRequest()?.HttpContext.Response;
-                if (response == null)
+                if (response is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1113));
                 }
 
                 var properties = context.Transaction.GetProperty<AuthenticationProperties>(typeof(AuthenticationProperties).FullName!);
-                if (properties != null && !string.IsNullOrEmpty(properties.RedirectUri))
+                if (properties is not null && !string.IsNullOrEmpty(properties.RedirectUri))
                 {
                     response.Redirect(properties.RedirectUri);
 
@@ -1345,7 +1345,7 @@ namespace OpenIddict.Server.AspNetCore
             /// <inheritdoc/>
             public ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }

src/OpenIddict.Server.AspNetCore/OpenIddictServerAspNetCoreHelpers.cs

@@ -25,7 +25,7 @@ namespace Microsoft.AspNetCore
         /// <returns>The <see cref="HttpRequest"/> instance or <c>null</c> if it couldn't be found.</returns>
         public static HttpRequest? GetHttpRequest(this OpenIddictServerTransaction transaction)
         {
-            if (transaction == null)
+            if (transaction is null)
             {
                 throw new ArgumentNullException(nameof(transaction));
             }
@@ -50,7 +50,7 @@ namespace Microsoft.AspNetCore
         /// <returns>The <see cref="OpenIddictServerEndpointType"/>.</returns>
         public static OpenIddictServerEndpointType GetOpenIddictServerEndpointType(this HttpContext context)
         {
-            if (context == null)
+            if (context is null)
             {
                 throw new ArgumentNullException(nameof(context));
             }
@@ -65,7 +65,7 @@ namespace Microsoft.AspNetCore
         /// <returns>The <see cref="OpenIddictRequest"/> instance or <c>null</c> if it couldn't be found.</returns>
         public static OpenIddictRequest? GetOpenIddictServerRequest(this HttpContext context)
         {
-            if (context == null)
+            if (context is null)
             {
                 throw new ArgumentNullException(nameof(context));
             }
@@ -80,7 +80,7 @@ namespace Microsoft.AspNetCore
         /// <returns>The <see cref="OpenIddictResponse"/> instance or <c>null</c> if it couldn't be found.</returns>
         public static OpenIddictResponse? GetOpenIddictServerResponse(this HttpContext context)
         {
-            if (context == null)
+            if (context is null)
             {
                 throw new ArgumentNullException(nameof(context));
             }

src/OpenIddict.Server.DataProtection/OpenIddictServerDataProtectionBuilder.cs

@@ -38,7 +38,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerDataProtectionBuilder"/>.</returns>
         public OpenIddictServerDataProtectionBuilder Configure(Action<OpenIddictServerDataProtectionOptions> configuration)
         {
-            if (configuration == null)
+            if (configuration is null)
             {
                 throw new ArgumentNullException(nameof(configuration));
             }
@@ -56,7 +56,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerDataProtectionBuilder"/>.</returns>
         public OpenIddictServerDataProtectionBuilder UseDataProtectionProvider(IDataProtectionProvider provider)
         {
-            if (provider == null)
+            if (provider is null)
             {
                 throw new ArgumentNullException(nameof(provider));
             }
@@ -71,7 +71,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerDataProtectionBuilder"/>.</returns>
         public OpenIddictServerDataProtectionBuilder UseFormatter(IOpenIddictServerDataProtectionFormatter formatter)
         {
-            if (formatter == null)
+            if (formatter is null)
             {
                 throw new ArgumentNullException(nameof(formatter));
             }

src/OpenIddict.Server.DataProtection/OpenIddictServerDataProtectionConfiguration.cs

@@ -27,7 +27,7 @@ namespace OpenIddict.Server.DataProtection
 
         public void Configure(OpenIddictServerOptions options)
         {
-            if (options == null)
+            if (options is null)
             {
                 throw new ArgumentNullException(nameof(options));
             }
@@ -44,7 +44,7 @@ namespace OpenIddict.Server.DataProtection
         /// <param name="options">The options instance to initialize.</param>
         public void PostConfigure(string name, OpenIddictServerDataProtectionOptions options)
         {
-            if (options == null)
+            if (options is null)
             {
                 throw new ArgumentNullException(nameof(options));
             }

src/OpenIddict.Server.DataProtection/OpenIddictServerDataProtectionExtensions.cs

@@ -29,7 +29,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public static OpenIddictServerDataProtectionBuilder UseDataProtection(this OpenIddictServerBuilder builder)
         {
-            if (builder == null)
+            if (builder is null)
             {
                 throw new ArgumentNullException(nameof(builder));
             }
@@ -68,12 +68,12 @@ namespace Microsoft.Extensions.DependencyInjection
         public static OpenIddictServerBuilder UseDataProtection(
             this OpenIddictServerBuilder builder, Action<OpenIddictServerDataProtectionBuilder> configuration)
         {
-            if (builder == null)
+            if (builder is null)
             {
                 throw new ArgumentNullException(nameof(builder));
             }
 
-            if (configuration == null)
+            if (configuration is null)
             {
                 throw new ArgumentNullException(nameof(configuration));
             }

src/OpenIddict.Server.DataProtection/OpenIddictServerDataProtectionFormatter.cs

@@ -22,13 +22,13 @@ namespace OpenIddict.Server.DataProtection
     {
         public ClaimsPrincipal? ReadToken(BinaryReader reader)
         {
-            if (reader == null)
+            if (reader is null)
             {
                 throw new ArgumentNullException(nameof(reader));
             }
 
             var (principal, properties) = Read(reader);
-            if (principal == null)
+            if (principal is null)
             {
                 return null;
             }
@@ -186,12 +186,12 @@ namespace OpenIddict.Server.DataProtection
 
         public void WriteToken(BinaryWriter writer, ClaimsPrincipal principal)
         {
-            if (writer == null)
+            if (writer is null)
             {
                 throw new ArgumentNullException(nameof(writer));
             }
 
-            if (principal == null)
+            if (principal is null)
             {
                 throw new ArgumentNullException(nameof(principal));
             }
@@ -303,7 +303,7 @@ namespace OpenIddict.Server.DataProtection
                     writer.Write(false);
                 }
 
-                if (identity.Actor != null)
+                if (identity.Actor is not null)
                 {
                     writer.Write(true);
                     WriteIdentity(writer, identity.Actor);
@@ -317,12 +317,12 @@ namespace OpenIddict.Server.DataProtection
 
             static void WriteClaim(BinaryWriter writer, Claim claim)
             {
-                if (writer == null)
+                if (writer is null)
                 {
                     throw new ArgumentNullException(nameof(writer));
                 }
 
-                if (claim == null)
+                if (claim is null)
                 {
                     throw new ArgumentNullException(nameof(claim));
                 }

src/OpenIddict.Server.DataProtection/OpenIddictServerDataProtectionHandlerFilters.cs

@@ -31,7 +31,7 @@ namespace OpenIddict.Server.DataProtection
 
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -53,7 +53,7 @@ namespace OpenIddict.Server.DataProtection
 
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -75,7 +75,7 @@ namespace OpenIddict.Server.DataProtection
 
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -97,7 +97,7 @@ namespace OpenIddict.Server.DataProtection
 
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -119,7 +119,7 @@ namespace OpenIddict.Server.DataProtection
 
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }

src/OpenIddict.Server.DataProtection/OpenIddictServerDataProtectionHandlers.cs

@@ -68,13 +68,13 @@ namespace OpenIddict.Server.DataProtection
             /// <inheritdoc/>
             public ValueTask HandleAsync(ProcessAuthenticationContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
 
                 // If a principal was already attached, don't overwrite it.
-                if (context.Principal != null)
+                if (context.Principal is not null)
                 {
                     return default;
                 }
@@ -94,7 +94,7 @@ namespace OpenIddict.Server.DataProtection
                     ValidateToken(context.Token, TokenTypeHints.DeviceCode)        ??
                     ValidateToken(context.Token, TokenTypeHints.UserCode);
 
-                if (principal == null)
+                if (principal is null)
                 {
                     context.Reject(
                         error: context.EndpointType switch
@@ -187,7 +187,7 @@ namespace OpenIddict.Server.DataProtection
             /// <inheritdoc/>
             public ValueTask HandleAsync(ProcessSignInContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -198,7 +198,7 @@ namespace OpenIddict.Server.DataProtection
                     return default;
                 }
 
-                if (context.AccessTokenPrincipal == null)
+                if (context.AccessTokenPrincipal is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1021));
                 }
@@ -250,7 +250,7 @@ namespace OpenIddict.Server.DataProtection
             /// <inheritdoc/>
             public ValueTask HandleAsync(ProcessSignInContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -261,7 +261,7 @@ namespace OpenIddict.Server.DataProtection
                     return default;
                 }
 
-                if (context.AuthorizationCodePrincipal == null)
+                if (context.AuthorizationCodePrincipal is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1021));
                 }
@@ -313,7 +313,7 @@ namespace OpenIddict.Server.DataProtection
             /// <inheritdoc/>
             public ValueTask HandleAsync(ProcessSignInContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -324,7 +324,7 @@ namespace OpenIddict.Server.DataProtection
                     return default;
                 }
 
-                if (context.DeviceCodePrincipal == null)
+                if (context.DeviceCodePrincipal is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1021));
                 }
@@ -376,7 +376,7 @@ namespace OpenIddict.Server.DataProtection
             /// <inheritdoc/>
             public ValueTask HandleAsync(ProcessSignInContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -387,7 +387,7 @@ namespace OpenIddict.Server.DataProtection
                     return default;
                 }
 
-                if (context.RefreshTokenPrincipal == null)
+                if (context.RefreshTokenPrincipal is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1021));
                 }
@@ -439,7 +439,7 @@ namespace OpenIddict.Server.DataProtection
             /// <inheritdoc/>
             public ValueTask HandleAsync(ProcessSignInContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -450,7 +450,7 @@ namespace OpenIddict.Server.DataProtection
                     return default;
                 }
 
-                if (context.UserCodePrincipal == null)
+                if (context.UserCodePrincipal is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1021));
                 }

src/OpenIddict.Server.Owin/OpenIddictServerOwinBuilder.cs

@@ -41,7 +41,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerOwinBuilder"/>.</returns>
         public OpenIddictServerOwinBuilder Configure(Action<OpenIddictServerOwinOptions> configuration)
         {
-            if (configuration == null)
+            if (configuration is null)
             {
                 throw new ArgumentNullException(nameof(configuration));
             }
@@ -161,7 +161,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerOwinBuilder"/>.</returns>
         public OpenIddictServerOwinBuilder SetAuthorizationEndpointCachingPolicy(DistributedCacheEntryOptions policy)
         {
-            if (policy == null)
+            if (policy is null)
             {
                 throw new ArgumentNullException(nameof(policy));
             }
@@ -177,7 +177,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerOwinBuilder"/>.</returns>
         public OpenIddictServerOwinBuilder SetLogoutEndpointCachingPolicy(DistributedCacheEntryOptions policy)
         {
-            if (policy == null)
+            if (policy is null)
             {
                 throw new ArgumentNullException(nameof(policy));
             }

src/OpenIddict.Server.Owin/OpenIddictServerOwinConfiguration.cs

@@ -19,7 +19,7 @@ namespace OpenIddict.Server.Owin
     {
         public void Configure(OpenIddictServerOptions options)
         {
-            if (options == null)
+            if (options is null)
             {
                 throw new ArgumentNullException(nameof(options));
             }
@@ -30,7 +30,7 @@ namespace OpenIddict.Server.Owin
 
         public void PostConfigure(string name, OpenIddictServerOwinOptions options)
         {
-            if (options == null)
+            if (options is null)
             {
                 throw new ArgumentNullException(nameof(options));
             }

src/OpenIddict.Server.Owin/OpenIddictServerOwinExtensions.cs

@@ -28,7 +28,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerOwinBuilder"/>.</returns>
         public static OpenIddictServerOwinBuilder UseOwin(this OpenIddictServerBuilder builder)
         {
-            if (builder == null)
+            if (builder is null)
             {
                 throw new ArgumentNullException(nameof(builder));
             }
@@ -77,12 +77,12 @@ namespace Microsoft.Extensions.DependencyInjection
         public static OpenIddictServerBuilder UseOwin(
             this OpenIddictServerBuilder builder, Action<OpenIddictServerOwinBuilder> configuration)
         {
-            if (builder == null)
+            if (builder is null)
             {
                 throw new ArgumentNullException(nameof(builder));
             }
 
-            if (configuration == null)
+            if (configuration is null)
             {
                 throw new ArgumentNullException(nameof(configuration));
             }

src/OpenIddict.Server.Owin/OpenIddictServerOwinHandler.cs

@@ -46,7 +46,7 @@ namespace OpenIddict.Server.Owin
             // Note: the transaction may be already attached when replaying an OWIN request
             // (e.g when using a status code pages middleware re-invoking the OWIN pipeline).
             var transaction = Context.Get<OpenIddictServerTransaction>(typeof(OpenIddictServerTransaction).FullName);
-            if (transaction == null)
+            if (transaction is null)
             {
                 // Create a new transaction and attach the OWIN request to make it available to the OWIN handlers.
                 transaction = await _factory.CreateTransactionAsync();
@@ -121,7 +121,7 @@ namespace OpenIddict.Server.Owin
         protected override async Task<AuthenticationTicket?> AuthenticateCoreAsync()
         {
             var transaction = Context.Get<OpenIddictServerTransaction>(typeof(OpenIddictServerTransaction).FullName);
-            if (transaction == null)
+            if (transaction is null)
             {
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID1111));
             }
@@ -130,7 +130,7 @@ namespace OpenIddict.Server.Owin
             // (generally later in the pipeline, when using the pass-through mode). To avoid having to re-validate it,
             // the authentication context is resolved from the transaction. If it's not available, a new one is created.
             var context = transaction.GetProperty<ProcessAuthenticationContext>(typeof(ProcessAuthenticationContext).FullName!);
-            if (context == null)
+            if (context is null)
             {
                 context = new ProcessAuthenticationContext(transaction);
                 await _dispatcher.DispatchAsync(context);
@@ -167,7 +167,7 @@ namespace OpenIddict.Server.Owin
 
             else
             {
-                Debug.Assert(context.Principal != null, SR.GetResourceString(SR.ID5006));
+                Debug.Assert(context.Principal is not null, SR.GetResourceString(SR.ID5006));
                 Debug.Assert(!string.IsNullOrEmpty(context.Principal.GetTokenType()), SR.GetResourceString(SR.ID5009));
                 Debug.Assert(!string.IsNullOrEmpty(context.Token), SR.GetResourceString(SR.ID5010));
 
@@ -201,7 +201,7 @@ namespace OpenIddict.Server.Owin
             // corresponds to a challenge response, as LookupChallenge() will always return a non-null
             // value when active authentication is used, even if no challenge was actually triggered.
             var challenge = Helper.LookupChallenge(Options.AuthenticationType, Options.AuthenticationMode);
-            if (challenge != null && (Response.StatusCode == 401 || Response.StatusCode == 403))
+            if (challenge is not null && (Response.StatusCode == 401 || Response.StatusCode == 403))
             {
                 var transaction = Context.Get<OpenIddictServerTransaction>(typeof(OpenIddictServerTransaction).FullName) ??
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1111));
@@ -244,7 +244,7 @@ namespace OpenIddict.Server.Owin
             }
 
             var signin = Helper.LookupSignIn(Options.AuthenticationType);
-            if (signin != null)
+            if (signin is not null)
             {
                 var transaction = Context.Get<OpenIddictServerTransaction>(typeof(OpenIddictServerTransaction).FullName) ??
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1111));
@@ -288,7 +288,7 @@ namespace OpenIddict.Server.Owin
             }
 
             var signout = Helper.LookupSignOut(Options.AuthenticationType, Options.AuthenticationMode);
-            if (signout != null)
+            if (signout is not null)
             {
                 var transaction = Context.Get<OpenIddictServerTransaction>(typeof(OpenIddictServerTransaction).FullName) ??
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1111));

src/OpenIddict.Server.Owin/OpenIddictServerOwinHandlerFilters.cs

@@ -29,7 +29,7 @@ namespace OpenIddict.Server.Owin
 
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -51,7 +51,7 @@ namespace OpenIddict.Server.Owin
 
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -72,7 +72,7 @@ namespace OpenIddict.Server.Owin
 
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -93,7 +93,7 @@ namespace OpenIddict.Server.Owin
 
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -115,7 +115,7 @@ namespace OpenIddict.Server.Owin
 
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -131,12 +131,12 @@ namespace OpenIddict.Server.Owin
         {
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
 
-                return new ValueTask<bool>(context.Transaction.GetOwinRequest() != null);
+                return new ValueTask<bool>(context.Transaction.GetOwinRequest() is not null);
             }
         }
 
@@ -152,7 +152,7 @@ namespace OpenIddict.Server.Owin
 
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -174,7 +174,7 @@ namespace OpenIddict.Server.Owin
 
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -196,7 +196,7 @@ namespace OpenIddict.Server.Owin
 
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -218,7 +218,7 @@ namespace OpenIddict.Server.Owin
 
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }

src/OpenIddict.Server.Owin/OpenIddictServerOwinHandlers.Authentication.cs

@@ -89,12 +89,12 @@ namespace OpenIddict.Server.Owin
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ExtractAuthorizationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
 
-                    Debug.Assert(context.Request != null, SR.GetResourceString(SR.ID5008));
+                    Debug.Assert(context.Request is not null, SR.GetResourceString(SR.ID5008));
 
                     // If a request_id parameter can be found in the authorization request,
                     // restore the complete authorization request from the distributed cache.
@@ -107,7 +107,7 @@ namespace OpenIddict.Server.Owin
                     // Note: the cache key is always prefixed with a specific marker
                     // to avoid collisions with the other types of cached payloads.
                     var token = await _cache.GetStringAsync(Cache.AuthorizationRequest + context.Request.RequestId);
-                    if (token == null || !context.Options.JsonWebTokenHandler.CanReadToken(token))
+                    if (token is null || !context.Options.JsonWebTokenHandler.CanReadToken(token))
                     {
                         context.Logger.LogError(SR.GetResourceString(SR.ID7146), Parameters.RequestId);
 
@@ -190,17 +190,17 @@ namespace OpenIddict.Server.Owin
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ExtractAuthorizationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
 
-                    Debug.Assert(context.Request != null, SR.GetResourceString(SR.ID5008));
+                    Debug.Assert(context.Request is not null, SR.GetResourceString(SR.ID5008));
 
                     // This handler only applies to OWIN requests. If The OWIN request cannot be resolved,
                     // this may indicate that the request was incorrectly processed by another server stack.
                     var request = context.Transaction.GetOwinRequest();
-                    if (request == null)
+                    if (request is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1119));
                     }
@@ -289,7 +289,7 @@ namespace OpenIddict.Server.Owin
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(ApplyAuthorizationResponseContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -334,7 +334,7 @@ namespace OpenIddict.Server.Owin
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ApplyAuthorizationResponseContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -342,7 +342,7 @@ namespace OpenIddict.Server.Owin
                     // This handler only applies to OWIN requests. If The OWIN request cannot be resolved,
                     // this may indicate that the request was incorrectly processed by another server stack.
                     var response = context.Transaction.GetOwinRequest()?.Context.Response;
-                    if (response == null)
+                    if (response is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1119));
                     }
@@ -374,7 +374,7 @@ namespace OpenIddict.Server.Owin
                         foreach (var (key, value) in
                             from parameter in context.Response.GetParameters()
                             let values = (string?[]?) parameter.Value
-                            where values != null
+                            where values is not null
                             from value in values
                             where !string.IsNullOrEmpty(value)
                             select (parameter.Key, Value: value))
@@ -425,7 +425,7 @@ namespace OpenIddict.Server.Owin
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(ApplyAuthorizationResponseContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -433,7 +433,7 @@ namespace OpenIddict.Server.Owin
                     // This handler only applies to OWIN requests. If The OWIN request cannot be resolved,
                     // this may indicate that the request was incorrectly processed by another server stack.
                     var response = context.Transaction.GetOwinRequest()?.Context.Response;
-                    if (response == null)
+                    if (response is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1119));
                     }
@@ -454,7 +454,7 @@ namespace OpenIddict.Server.Owin
                     foreach (var (key, value) in
                         from parameter in context.Response.GetParameters()
                         let values = (string?[]?) parameter.Value
-                        where values != null
+                        where values is not null
                         from value in values
                         where !string.IsNullOrEmpty(value)
                         select (parameter.Key, Value: value))
@@ -489,7 +489,7 @@ namespace OpenIddict.Server.Owin
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(ApplyAuthorizationResponseContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -497,7 +497,7 @@ namespace OpenIddict.Server.Owin
                     // This handler only applies to OWIN requests. If The OWIN request cannot be resolved,
                     // this may indicate that the request was incorrectly processed by another server stack.
                     var response = context.Transaction.GetOwinRequest()?.Context.Response;
-                    if (response == null)
+                    if (response is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1119));
                     }
@@ -518,7 +518,7 @@ namespace OpenIddict.Server.Owin
                     foreach (var (key, value) in
                         from parameter in context.Response.GetParameters()
                         let values = (string?[]?) parameter.Value
-                        where values != null
+                        where values is not null
                         from value in values
                         where !string.IsNullOrEmpty(value)
                         select (parameter.Key, Value: value))

src/OpenIddict.Server.Owin/OpenIddictServerOwinHandlers.Session.cs

@@ -86,12 +86,12 @@ namespace OpenIddict.Server.Owin
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ExtractLogoutRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
 
-                    Debug.Assert(context.Request != null, SR.GetResourceString(SR.ID5008));
+                    Debug.Assert(context.Request is not null, SR.GetResourceString(SR.ID5008));
 
                     // If a request_id parameter can be found in the logout request,
                     // restore the complete logout request from the distributed cache.
@@ -104,7 +104,7 @@ namespace OpenIddict.Server.Owin
                     // Note: the cache key is always prefixed with a specific marker
                     // to avoid collisions with the other types of cached payloads.
                     var token = await _cache.GetStringAsync(Cache.LogoutRequest + context.Request.RequestId);
-                    if (token == null || !context.Options.JsonWebTokenHandler.CanReadToken(token))
+                    if (token is null || !context.Options.JsonWebTokenHandler.CanReadToken(token))
                     {
                         context.Logger.LogError(SR.GetResourceString(SR.ID7150), Parameters.RequestId);
 
@@ -187,17 +187,17 @@ namespace OpenIddict.Server.Owin
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ExtractLogoutRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
 
-                    Debug.Assert(context.Request != null, SR.GetResourceString(SR.ID5008));
+                    Debug.Assert(context.Request is not null, SR.GetResourceString(SR.ID5008));
 
                     // This handler only applies to OWIN requests. If The OWIN request cannot be resolved,
                     // this may indicate that the request was incorrectly processed by another server stack.
                     var request = context.Transaction.GetOwinRequest();
-                    if (request == null)
+                    if (request is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1119));
                     }
@@ -286,7 +286,7 @@ namespace OpenIddict.Server.Owin
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(ApplyLogoutResponseContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -326,7 +326,7 @@ namespace OpenIddict.Server.Owin
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(ApplyLogoutResponseContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -334,7 +334,7 @@ namespace OpenIddict.Server.Owin
                     // This handler only applies to OWIN requests. If The OWIN request cannot be resolved,
                     // this may indicate that the request was incorrectly processed by another server stack.
                     var response = context.Transaction.GetOwinRequest()?.Context.Response;
-                    if (response == null)
+                    if (response is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1119));
                     }
@@ -354,7 +354,7 @@ namespace OpenIddict.Server.Owin
                     foreach (var (key, value) in
                         from parameter in context.Response.GetParameters()
                         let values = (string?[]?) parameter.Value
-                        where values != null
+                        where values is not null
                         from value in values
                         where !string.IsNullOrEmpty(value)
                         select (parameter.Key, Value: value))

src/OpenIddict.Server.Owin/OpenIddictServerOwinHandlers.cs

@@ -75,7 +75,7 @@ namespace OpenIddict.Server.Owin
             /// <inheritdoc/>
             public ValueTask HandleAsync(ProcessRequestContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -83,7 +83,7 @@ namespace OpenIddict.Server.Owin
                 // This handler only applies to OWIN requests. If The OWIN request cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var request = context.Transaction.GetOwinRequest();
-                if (request == null)
+                if (request is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1119));
                 }
@@ -177,7 +177,7 @@ namespace OpenIddict.Server.Owin
             /// <inheritdoc/>
             public ValueTask HandleAsync(ProcessRequestContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -185,14 +185,14 @@ namespace OpenIddict.Server.Owin
                 // This handler only applies to OWIN requests. If The OWIN request cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var request = context.Transaction.GetOwinRequest();
-                if (request == null)
+                if (request is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1119));
                 }
 
                 // Don't require that the request host be present if the request is not handled
                 // by an OpenIddict endpoint or if an explicit issuer URL was already set.
-                if (context.Issuer != null || context.EndpointType == OpenIddictServerEndpointType.Unknown)
+                if (context.Issuer is not null || context.EndpointType == OpenIddictServerEndpointType.Unknown)
                 {
                     return default;
                 }
@@ -243,7 +243,7 @@ namespace OpenIddict.Server.Owin
             /// <inheritdoc/>
             public ValueTask HandleAsync(ProcessRequestContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -251,7 +251,7 @@ namespace OpenIddict.Server.Owin
                 // This handler only applies to OWIN requests. If The OWIN request cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var request = context.Transaction.GetOwinRequest();
-                if (request == null)
+                if (request is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1119));
                 }
@@ -296,13 +296,13 @@ namespace OpenIddict.Server.Owin
             /// <inheritdoc/>
             public ValueTask HandleAsync(ProcessChallengeContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
 
                 var properties = context.Transaction.GetProperty<AuthenticationProperties>(typeof(AuthenticationProperties).FullName!);
-                if (properties != null)
+                if (properties is not null)
                 {
                     context.Response.Error = GetProperty(properties, Properties.Error);
                     context.Response.ErrorDescription = GetProperty(properties, Properties.ErrorDescription);
@@ -337,7 +337,7 @@ namespace OpenIddict.Server.Owin
             /// <inheritdoc/>
             public ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -345,7 +345,7 @@ namespace OpenIddict.Server.Owin
                 // This handler only applies to OWIN requests. If The OWIN request cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var request = context.Transaction.GetOwinRequest();
-                if (request == null)
+                if (request is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1119));
                 }
@@ -390,7 +390,7 @@ namespace OpenIddict.Server.Owin
             /// <inheritdoc/>
             public async ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -398,7 +398,7 @@ namespace OpenIddict.Server.Owin
                 // This handler only applies to OWIN requests. If The OWIN request cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var request = context.Transaction.GetOwinRequest();
-                if (request == null)
+                if (request is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1119));
                 }
@@ -470,7 +470,7 @@ namespace OpenIddict.Server.Owin
             /// <inheritdoc/>
             public async ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -478,7 +478,7 @@ namespace OpenIddict.Server.Owin
                 // This handler only applies to OWIN requests. If The OWIN request cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var request = context.Transaction.GetOwinRequest();
-                if (request == null)
+                if (request is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1119));
                 }
@@ -546,17 +546,17 @@ namespace OpenIddict.Server.Owin
             /// <inheritdoc/>
             public ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
 
-                Debug.Assert(context.Transaction.Request != null, SR.GetResourceString(SR.ID5008));
+                Debug.Assert(context.Transaction.Request is not null, SR.GetResourceString(SR.ID5008));
 
                 // This handler only applies to OWIN requests. If The OWIN request cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var request = context.Transaction.GetOwinRequest();
-                if (request == null)
+                if (request is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1119));
                 }
@@ -645,17 +645,17 @@ namespace OpenIddict.Server.Owin
             /// <inheritdoc/>
             public ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
 
-                Debug.Assert(context.Transaction.Request != null, SR.GetResourceString(SR.ID5008));
+                Debug.Assert(context.Transaction.Request is not null, SR.GetResourceString(SR.ID5008));
 
                 // This handler only applies to OWIN requests. If The OWIN request cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var request = context.Transaction.GetOwinRequest();
-                if (request == null)
+                if (request is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1119));
                 }
@@ -696,7 +696,7 @@ namespace OpenIddict.Server.Owin
             /// <inheritdoc/>
             public ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -727,17 +727,17 @@ namespace OpenIddict.Server.Owin
             /// <inheritdoc/>
             public ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
 
-                Debug.Assert(context.Transaction.Response != null, SR.GetResourceString(SR.ID5007));
+                Debug.Assert(context.Transaction.Response is not null, SR.GetResourceString(SR.ID5007));
 
                 // This handler only applies to OWIN requests. If The OWIN request cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var response = context.Transaction.GetOwinRequest()?.Context.Response;
-                if (response == null)
+                if (response is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1119));
                 }
@@ -787,7 +787,7 @@ namespace OpenIddict.Server.Owin
             /// <inheritdoc/>
             public ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -795,7 +795,7 @@ namespace OpenIddict.Server.Owin
                 // This handler only applies to OWIN requests. If The OWIN request cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var response = context.Transaction.GetOwinRequest()?.Context.Response;
-                if (response == null)
+                if (response is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1119));
                 }
@@ -834,17 +834,17 @@ namespace OpenIddict.Server.Owin
             /// <inheritdoc/>
             public ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
 
-                Debug.Assert(context.Transaction.Response != null, SR.GetResourceString(SR.ID5007));
+                Debug.Assert(context.Transaction.Response is not null, SR.GetResourceString(SR.ID5007));
 
                 // This handler only applies to OWIN requests. If The OWIN request cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var response = context.Transaction.GetOwinRequest()?.Context.Response;
-                if (response == null)
+                if (response is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1119));
                 }
@@ -948,7 +948,7 @@ namespace OpenIddict.Server.Owin
             /// <inheritdoc/>
             public ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -956,7 +956,7 @@ namespace OpenIddict.Server.Owin
                 // This handler only applies to OWIN requests. If The OWIN request cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var response = context.Transaction.GetOwinRequest()?.Context.Response;
-                if (response == null)
+                if (response is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1119));
                 }
@@ -994,7 +994,7 @@ namespace OpenIddict.Server.Owin
             /// <inheritdoc/>
             public async ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -1002,7 +1002,7 @@ namespace OpenIddict.Server.Owin
                 // This handler only applies to OWIN requests. If The OWIN request cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var response = context.Transaction.GetOwinRequest()?.Context.Response;
-                if (response == null)
+                if (response is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1119));
                 }
@@ -1051,17 +1051,17 @@ namespace OpenIddict.Server.Owin
             /// <inheritdoc/>
             public ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
 
-                Debug.Assert(context.Transaction.Response != null, SR.GetResourceString(SR.ID5007));
+                Debug.Assert(context.Transaction.Response is not null, SR.GetResourceString(SR.ID5007));
 
                 // This handler only applies to OWIN requests. If The OWIN request cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var response = context.Transaction.GetOwinRequest()?.Context.Response;
-                if (response == null)
+                if (response is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1119));
                 }
@@ -1101,17 +1101,17 @@ namespace OpenIddict.Server.Owin
             /// <inheritdoc/>
             public async ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
 
-                Debug.Assert(context.Transaction.Response != null, SR.GetResourceString(SR.ID5007));
+                Debug.Assert(context.Transaction.Response is not null, SR.GetResourceString(SR.ID5007));
 
                 // This handler only applies to OWIN requests. If The OWIN request cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var response = context.Transaction.GetOwinRequest()?.Context.Response;
-                if (response == null)
+                if (response is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1119));
                 }
@@ -1178,7 +1178,7 @@ namespace OpenIddict.Server.Owin
             /// <inheritdoc/>
             public ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -1186,13 +1186,13 @@ namespace OpenIddict.Server.Owin
                 // This handler only applies to OWIN requests. If The OWIN request cannot be resolved,
                 // this may indicate that the request was incorrectly processed by another server stack.
                 var response = context.Transaction.GetOwinRequest()?.Context.Response;
-                if (response == null)
+                if (response is null)
                 {
                     throw new InvalidOperationException(SR.GetResourceString(SR.ID1119));
                 }
 
                 var properties = context.Transaction.GetProperty<AuthenticationProperties>(typeof(AuthenticationProperties).FullName!);
-                if (properties != null && !string.IsNullOrEmpty(properties.RedirectUri))
+                if (properties is not null && !string.IsNullOrEmpty(properties.RedirectUri))
                 {
                     response.Redirect(properties.RedirectUri);
 
@@ -1225,7 +1225,7 @@ namespace OpenIddict.Server.Owin
             /// <inheritdoc/>
             public ValueTask HandleAsync(TContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }

src/OpenIddict.Server.Owin/OpenIddictServerOwinHelpers.cs

@@ -27,7 +27,7 @@ namespace Owin
         /// <returns>The <see cref="IAppBuilder"/>.</returns>
         public static IAppBuilder UseOpenIddictServer(this IAppBuilder app)
         {
-            if (app == null)
+            if (app is null)
             {
                 throw new ArgumentNullException(nameof(app));
             }
@@ -42,7 +42,7 @@ namespace Owin
         /// <returns>The <see cref="IOwinRequest"/> instance or <c>null</c> if it couldn't be found.</returns>
         public static IOwinRequest? GetOwinRequest(this OpenIddictServerTransaction transaction)
         {
-            if (transaction == null)
+            if (transaction is null)
             {
                 throw new ArgumentNullException(nameof(transaction));
             }
@@ -67,7 +67,7 @@ namespace Owin
         /// <returns>The <see cref="OpenIddictServerEndpointType"/>.</returns>
         public static OpenIddictServerEndpointType GetOpenIddictServerEndpointType(this IOwinContext context)
         {
-            if (context == null)
+            if (context is null)
             {
                 throw new ArgumentNullException(nameof(context));
             }
@@ -82,7 +82,7 @@ namespace Owin
         /// <returns>The <see cref="OpenIddictRequest"/> instance or <c>null</c> if it couldn't be found.</returns>
         public static OpenIddictRequest? GetOpenIddictServerRequest(this IOwinContext context)
         {
-            if (context == null)
+            if (context is null)
             {
                 throw new ArgumentNullException(nameof(context));
             }
@@ -97,7 +97,7 @@ namespace Owin
         /// <returns>The <see cref="OpenIddictResponse"/> instance or <c>null</c> if it couldn't be found.</returns>
         public static OpenIddictResponse? GetOpenIddictServerResponse(this IOwinContext context)
         {
-            if (context == null)
+            if (context is null)
             {
                 throw new ArgumentNullException(nameof(context));
             }

src/OpenIddict.Server.Owin/OpenIddictServerOwinMiddlewareFactory.cs

@@ -39,13 +39,13 @@ namespace OpenIddict.Server.Owin
         /// </returns>
         public override Task Invoke(IOwinContext context)
         {
-            if (context == null)
+            if (context is null)
             {
                 throw new ArgumentNullException(nameof(context));
             }
 
             var provider = context.Get<IServiceProvider>(typeof(IServiceProvider).FullName);
-            if (provider == null)
+            if (provider is null)
             {
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID1120));
             }

src/OpenIddict.Server.Quartz/OpenIddictServerQuartzBuilder.cs

@@ -38,7 +38,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerQuartzBuilder"/>.</returns>
         public OpenIddictServerQuartzBuilder Configure(Action<OpenIddictServerQuartzOptions> configuration)
         {
-            if (configuration == null)
+            if (configuration is null)
             {
                 throw new ArgumentNullException(nameof(configuration));
             }

src/OpenIddict.Server.Quartz/OpenIddictServerQuartzExtensions.cs

@@ -26,7 +26,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerQuartzBuilder"/>.</returns>
         public static OpenIddictServerQuartzBuilder UseQuartz(this OpenIddictServerBuilder builder)
         {
-            if (builder == null)
+            if (builder is null)
             {
                 throw new ArgumentNullException(nameof(builder));
             }
@@ -83,12 +83,12 @@ namespace Microsoft.Extensions.DependencyInjection
         public static OpenIddictServerBuilder UseQuartz(
             this OpenIddictServerBuilder builder, Action<OpenIddictServerQuartzBuilder> configuration)
         {
-            if (builder == null)
+            if (builder is null)
             {
                 throw new ArgumentNullException(nameof(builder));
             }
 
-            if (configuration == null)
+            if (configuration is null)
             {
                 throw new ArgumentNullException(nameof(configuration));
             }

src/OpenIddict.Server.Quartz/OpenIddictServerQuartzJob.cs

@@ -50,7 +50,7 @@ namespace OpenIddict.Server.Quartz
         /// <inheritdoc/>
         public async Task Execute(IJobExecutionContext context)
         {
-            if (context == null)
+            if (context is null)
             {
                 throw new ArgumentNullException(nameof(context));
             }
@@ -71,7 +71,7 @@ namespace OpenIddict.Server.Quartz
                 if (!_options.CurrentValue.DisableTokenPruning)
                 {
                     var manager = scope.ServiceProvider.GetService<IOpenIddictTokenManager>();
-                    if (manager == null)
+                    if (manager is null)
                     {
                         // Inform Quartz.NET that the triggers associated with this job should be removed,
                         // as the future invocations will always fail until the application is correctly
@@ -128,7 +128,7 @@ namespace OpenIddict.Server.Quartz
                 if (!_options.CurrentValue.DisableAuthorizationPruning)
                 {
                     var manager = scope.ServiceProvider.GetService<IOpenIddictAuthorizationManager>();
-                    if (manager == null)
+                    if (manager is null)
                     {
                         // Inform Quartz.NET that the triggers associated with this job should be removed,
                         // as the future invocations will always fail until the application is correctly
@@ -182,7 +182,7 @@ namespace OpenIddict.Server.Quartz
                     }
                 }
 
-                if (exceptions != null)
+                if (exceptions is not null)
                 {
                     throw new JobExecutionException(new AggregateException(exceptions))
                     {

src/OpenIddict.Server/OpenIddictServerBuilder.cs

@@ -50,7 +50,7 @@ namespace Microsoft.Extensions.DependencyInjection
             Action<OpenIddictServerHandlerDescriptor.Builder<TContext>> configuration)
             where TContext : OpenIddictServerEvents.BaseContext
         {
-            if (configuration == null)
+            if (configuration is null)
             {
                 throw new ArgumentNullException(nameof(configuration));
             }
@@ -72,7 +72,7 @@ namespace Microsoft.Extensions.DependencyInjection
         [EditorBrowsable(EditorBrowsableState.Advanced)]
         public OpenIddictServerBuilder AddEventHandler(OpenIddictServerHandlerDescriptor descriptor)
         {
-            if (descriptor == null)
+            if (descriptor is null)
             {
                 throw new ArgumentNullException(nameof(descriptor));
             }
@@ -91,7 +91,7 @@ namespace Microsoft.Extensions.DependencyInjection
         [EditorBrowsable(EditorBrowsableState.Advanced)]
         public OpenIddictServerBuilder RemoveEventHandler(OpenIddictServerHandlerDescriptor descriptor)
         {
-            if (descriptor == null)
+            if (descriptor is null)
             {
                 throw new ArgumentNullException(nameof(descriptor));
             }
@@ -120,7 +120,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder Configure(Action<OpenIddictServerOptions> configuration)
         {
-            if (configuration == null)
+            if (configuration is null)
             {
                 throw new ArgumentNullException(nameof(configuration));
             }
@@ -146,7 +146,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder AddEncryptionCredentials(EncryptingCredentials credentials)
         {
-            if (credentials == null)
+            if (credentials is null)
             {
                 throw new ArgumentNullException(nameof(credentials));
             }
@@ -161,7 +161,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder AddEncryptionKey(SecurityKey key)
         {
-            if (key == null)
+            if (key is null)
             {
                 throw new ArgumentNullException(nameof(key));
             }
@@ -204,7 +204,7 @@ namespace Microsoft.Extensions.DependencyInjection
             Justification = "The X.509 certificate is attached to the server options.")]
         public OpenIddictServerBuilder AddDevelopmentEncryptionCertificate(X500DistinguishedName subject)
         {
-            if (subject == null)
+            if (subject is null)
             {
                 throw new ArgumentNullException(nameof(subject));
             }
@@ -219,7 +219,7 @@ namespace Microsoft.Extensions.DependencyInjection
                 .OfType<X509Certificate2>()
                 .SingleOrDefault();
 
-            if (certificate != null && (certificate.NotBefore > DateTime.Now || certificate.NotAfter < DateTime.Now))
+            if (certificate is not null && (certificate.NotBefore > DateTime.Now || certificate.NotAfter < DateTime.Now))
             {
                 store.Remove(certificate);
                 certificate = null;
@@ -227,7 +227,7 @@ namespace Microsoft.Extensions.DependencyInjection
 
 #if SUPPORTS_CERTIFICATE_GENERATION
             // If no appropriate certificate can be found, generate and persist a new certificate in the specified store.
-            if (certificate == null)
+            if (certificate is null)
             {
                 using var algorithm = RSA.Create(keySizeInBits: 2048);
 
@@ -370,7 +370,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder AddEncryptionCertificate(X509Certificate2 certificate)
         {
-            if (certificate == null)
+            if (certificate is null)
             {
                 throw new ArgumentNullException(nameof(certificate));
             }
@@ -423,7 +423,7 @@ namespace Microsoft.Extensions.DependencyInjection
             Assembly assembly, string resource,
             string password, X509KeyStorageFlags flags)
         {
-            if (assembly == null)
+            if (assembly is null)
             {
                 throw new ArgumentNullException(nameof(assembly));
             }
@@ -439,7 +439,7 @@ namespace Microsoft.Extensions.DependencyInjection
             }
 
             using var stream = assembly.GetManifestResourceStream(resource);
-            if (stream == null)
+            if (stream is null)
             {
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID1063));
             }
@@ -477,7 +477,7 @@ namespace Microsoft.Extensions.DependencyInjection
             Justification = "The X.509 certificate is attached to the server options.")]
         public OpenIddictServerBuilder AddEncryptionCertificate(Stream stream, string password, X509KeyStorageFlags flags)
         {
-            if (stream == null)
+            if (stream is null)
             {
                 throw new ArgumentNullException(nameof(stream));
             }
@@ -506,7 +506,7 @@ namespace Microsoft.Extensions.DependencyInjection
             }
 
             var certificate = GetCertificate(StoreLocation.CurrentUser, thumbprint) ?? GetCertificate(StoreLocation.LocalMachine, thumbprint);
-            if (certificate == null)
+            if (certificate is null)
             {
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID1065));
             }
@@ -545,7 +545,7 @@ namespace Microsoft.Extensions.DependencyInjection
                 .OfType<X509Certificate2>()
                 .SingleOrDefault();
 
-            if (certificate == null)
+            if (certificate is null)
             {
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID1065));
             }
@@ -560,7 +560,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder AddSigningCredentials(SigningCredentials credentials)
         {
-            if (credentials == null)
+            if (credentials is null)
             {
                 throw new ArgumentNullException(nameof(credentials));
             }
@@ -575,7 +575,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder AddSigningKey(SecurityKey key)
         {
-            if (key == null)
+            if (key is null)
             {
                 throw new ArgumentNullException(nameof(key));
             }
@@ -641,7 +641,7 @@ namespace Microsoft.Extensions.DependencyInjection
             Justification = "The X.509 certificate is attached to the server options.")]
         public OpenIddictServerBuilder AddDevelopmentSigningCertificate(X500DistinguishedName subject)
         {
-            if (subject == null)
+            if (subject is null)
             {
                 throw new ArgumentNullException(nameof(subject));
             }
@@ -656,7 +656,7 @@ namespace Microsoft.Extensions.DependencyInjection
                 .OfType<X509Certificate2>()
                 .SingleOrDefault();
 
-            if (certificate != null && (certificate.NotBefore > DateTime.Now || certificate.NotAfter < DateTime.Now))
+            if (certificate is not null && (certificate.NotBefore > DateTime.Now || certificate.NotAfter < DateTime.Now))
             {
                 store.Remove(certificate);
                 certificate = null;
@@ -664,7 +664,7 @@ namespace Microsoft.Extensions.DependencyInjection
 
 #if SUPPORTS_CERTIFICATE_GENERATION
             // If no appropriate certificate can be found, generate and persist a new certificate in the specified store.
-            if (certificate == null)
+            if (certificate is null)
             {
                 using var algorithm = RSA.Create(keySizeInBits: 2048);
 
@@ -826,7 +826,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder AddSigningCertificate(X509Certificate2 certificate)
         {
-            if (certificate == null)
+            if (certificate is null)
             {
                 throw new ArgumentNullException(nameof(certificate));
             }
@@ -879,7 +879,7 @@ namespace Microsoft.Extensions.DependencyInjection
             Assembly assembly, string resource,
             string password, X509KeyStorageFlags flags)
         {
-            if (assembly == null)
+            if (assembly is null)
             {
                 throw new ArgumentNullException(nameof(assembly));
             }
@@ -895,7 +895,7 @@ namespace Microsoft.Extensions.DependencyInjection
             }
 
             using var stream = assembly.GetManifestResourceStream(resource);
-            if (stream == null)
+            if (stream is null)
             {
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID1063));
             }
@@ -933,7 +933,7 @@ namespace Microsoft.Extensions.DependencyInjection
             Justification = "The X.509 certificate is attached to the server options.")]
         public OpenIddictServerBuilder AddSigningCertificate(Stream stream, string password, X509KeyStorageFlags flags)
         {
-            if (stream == null)
+            if (stream is null)
             {
                 throw new ArgumentNullException(nameof(stream));
             }
@@ -962,7 +962,7 @@ namespace Microsoft.Extensions.DependencyInjection
             }
 
             var certificate = GetCertificate(StoreLocation.CurrentUser, thumbprint) ?? GetCertificate(StoreLocation.LocalMachine, thumbprint);
-            if (certificate == null)
+            if (certificate is null)
             {
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID1065));
             }
@@ -1001,7 +1001,7 @@ namespace Microsoft.Extensions.DependencyInjection
                 .OfType<X509Certificate2>()
                 .SingleOrDefault();
 
-            if (certificate == null)
+            if (certificate is null)
             {
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID1065));
             }
@@ -1085,7 +1085,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder SetAuthorizationEndpointUris(params string[] addresses)
         {
-            if (addresses == null)
+            if (addresses is null)
             {
                 throw new ArgumentNullException(nameof(addresses));
             }
@@ -1102,7 +1102,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder SetAuthorizationEndpointUris(params Uri[] addresses)
         {
-            if (addresses == null)
+            if (addresses is null)
             {
                 throw new ArgumentNullException(nameof(addresses));
             }
@@ -1133,7 +1133,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder SetConfigurationEndpointUris(params string[] addresses)
         {
-            if (addresses == null)
+            if (addresses is null)
             {
                 throw new ArgumentNullException(nameof(addresses));
             }
@@ -1150,7 +1150,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder SetConfigurationEndpointUris(params Uri[] addresses)
         {
-            if (addresses == null)
+            if (addresses is null)
             {
                 throw new ArgumentNullException(nameof(addresses));
             }
@@ -1181,7 +1181,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder SetCryptographyEndpointUris(params string[] addresses)
         {
-            if (addresses == null)
+            if (addresses is null)
             {
                 throw new ArgumentNullException(nameof(addresses));
             }
@@ -1198,7 +1198,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder SetCryptographyEndpointUris(params Uri[] addresses)
         {
-            if (addresses == null)
+            if (addresses is null)
             {
                 throw new ArgumentNullException(nameof(addresses));
             }
@@ -1229,7 +1229,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder SetDeviceEndpointUris(params string[] addresses)
         {
-            if (addresses == null)
+            if (addresses is null)
             {
                 throw new ArgumentNullException(nameof(addresses));
             }
@@ -1246,7 +1246,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder SetDeviceEndpointUris(params Uri[] addresses)
         {
-            if (addresses == null)
+            if (addresses is null)
             {
                 throw new ArgumentNullException(nameof(addresses));
             }
@@ -1277,7 +1277,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder SetIntrospectionEndpointUris(params string[] addresses)
         {
-            if (addresses == null)
+            if (addresses is null)
             {
                 throw new ArgumentNullException(nameof(addresses));
             }
@@ -1294,7 +1294,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder SetIntrospectionEndpointUris(params Uri[] addresses)
         {
-            if (addresses == null)
+            if (addresses is null)
             {
                 throw new ArgumentNullException(nameof(addresses));
             }
@@ -1325,7 +1325,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder SetLogoutEndpointUris(params string[] addresses)
         {
-            if (addresses == null)
+            if (addresses is null)
             {
                 throw new ArgumentNullException(nameof(addresses));
             }
@@ -1342,7 +1342,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder SetLogoutEndpointUris(params Uri[] addresses)
         {
-            if (addresses == null)
+            if (addresses is null)
             {
                 throw new ArgumentNullException(nameof(addresses));
             }
@@ -1373,7 +1373,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder SetRevocationEndpointUris(params string[] addresses)
         {
-            if (addresses == null)
+            if (addresses is null)
             {
                 throw new ArgumentNullException(nameof(addresses));
             }
@@ -1390,7 +1390,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder SetRevocationEndpointUris(params Uri[] addresses)
         {
-            if (addresses == null)
+            if (addresses is null)
             {
                 throw new ArgumentNullException(nameof(addresses));
             }
@@ -1421,7 +1421,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder SetTokenEndpointUris(params string[] addresses)
         {
-            if (addresses == null)
+            if (addresses is null)
             {
                 throw new ArgumentNullException(nameof(addresses));
             }
@@ -1438,7 +1438,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder SetTokenEndpointUris(params Uri[] addresses)
         {
-            if (addresses == null)
+            if (addresses is null)
             {
                 throw new ArgumentNullException(nameof(addresses));
             }
@@ -1469,7 +1469,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder SetUserinfoEndpointUris(params string[] addresses)
         {
-            if (addresses == null)
+            if (addresses is null)
             {
                 throw new ArgumentNullException(nameof(addresses));
             }
@@ -1486,7 +1486,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder SetUserinfoEndpointUris(params Uri[] addresses)
         {
-            if (addresses == null)
+            if (addresses is null)
             {
                 throw new ArgumentNullException(nameof(addresses));
             }
@@ -1517,7 +1517,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder SetVerificationEndpointUris(params string[] addresses)
         {
-            if (addresses == null)
+            if (addresses is null)
             {
                 throw new ArgumentNullException(nameof(addresses));
             }
@@ -1534,7 +1534,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder SetVerificationEndpointUris(params Uri[] addresses)
         {
-            if (addresses == null)
+            if (addresses is null)
             {
                 throw new ArgumentNullException(nameof(addresses));
             }
@@ -1646,7 +1646,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder RegisterClaims(params string[] claims)
         {
-            if (claims == null)
+            if (claims is null)
             {
                 throw new ArgumentNullException(nameof(claims));
             }
@@ -1667,7 +1667,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder RegisterScopes(params string[] scopes)
         {
-            if (scopes == null)
+            if (scopes is null)
             {
                 throw new ArgumentNullException(nameof(scopes));
             }
@@ -1754,7 +1754,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public OpenIddictServerBuilder SetIssuer(Uri address)
         {
-            if (address == null)
+            if (address is null)
             {
                 throw new ArgumentNullException(nameof(address));
             }

src/OpenIddict.Server/OpenIddictServerConfiguration.cs

@@ -29,7 +29,7 @@ namespace OpenIddict.Server
         /// <param name="options">The options instance to initialize.</param>
         public void PostConfigure(string name, OpenIddictServerOptions options)
         {
-            if (options == null)
+            if (options is null)
             {
                 throw new ArgumentNullException(nameof(options));
             }
@@ -48,7 +48,7 @@ namespace OpenIddict.Server
                 options.UseRollingRefreshTokens |= !options.UseRollingRefreshTokens && !options.DisableSlidingRefreshTokenExpiration;
             }
 
-            if (options.JsonWebTokenHandler == null)
+            if (options.JsonWebTokenHandler is null)
             {
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID1074));
             }
@@ -284,23 +284,23 @@ namespace OpenIddict.Server
                 (SecurityKey first, SecurityKey second) when ReferenceEquals(first, second) => 0,
 
                 // If one of the keys is a symmetric key, prefer it to the other one.
-                (SymmetricSecurityKey _, SymmetricSecurityKey _) => 0,
-                (SymmetricSecurityKey _, SecurityKey _)          => -1,
-                (SecurityKey _, SymmetricSecurityKey _)          => 1,
+                (SymmetricSecurityKey, SymmetricSecurityKey) => 0,
+                (SymmetricSecurityKey, SecurityKey)          => -1,
+                (SecurityKey, SymmetricSecurityKey)          => 1,
 
                 // If one of the keys is backed by a X.509 certificate, don't prefer it if it's not valid yet.
-                (X509SecurityKey first, SecurityKey _)  when first.Certificate.NotBefore  > DateTime.Now => 1,
-                (SecurityKey _, X509SecurityKey second) when second.Certificate.NotBefore > DateTime.Now => 1,
+                (X509SecurityKey first, SecurityKey)  when first.Certificate.NotBefore  > DateTime.Now => 1,
+                (SecurityKey, X509SecurityKey second) when second.Certificate.NotBefore > DateTime.Now => 1,
 
                 // If the two keys are backed by a X.509 certificate, prefer the one with the furthest expiration date.
                 (X509SecurityKey first, X509SecurityKey second) => -first.Certificate.NotAfter.CompareTo(second.Certificate.NotAfter),
 
                 // If one of the keys is backed by a X.509 certificate, prefer the X.509 security key.
-                (X509SecurityKey _, SecurityKey _) => -1,
-                (SecurityKey _, X509SecurityKey _) => 1,
+                (X509SecurityKey, SecurityKey) => -1,
+                (SecurityKey, X509SecurityKey) => 1,
 
                 // If the two keys are not backed by a X.509 certificate, none should be preferred to the other.
-                (SecurityKey _, SecurityKey _) => 0
+                (SecurityKey, SecurityKey) => 0
             };
 
             static string? GetKeyIdentifier(SecurityKey key)
@@ -319,11 +319,11 @@ namespace OpenIddict.Server
                     // Note: if the RSA parameters are not attached to the signing key,
                     // extract them by calling ExportParameters on the RSA instance.
                     var parameters = rsaSecurityKey.Parameters;
-                    if (parameters.Modulus == null)
+                    if (parameters.Modulus is null)
                     {
                         parameters = rsaSecurityKey.Rsa.ExportParameters(includePrivateParameters: false);
 
-                        Debug.Assert(parameters.Modulus != null, SR.GetResourceString(SR.ID5003));
+                        Debug.Assert(parameters.Modulus is not null, SR.GetResourceString(SR.ID5003));
                     }
 
                     // Only use the 40 first chars of the base64url-encoded modulus.
@@ -337,7 +337,7 @@ namespace OpenIddict.Server
                     // Extract the ECDSA parameters from the signing credentials.
                     var parameters = ecsdaSecurityKey.ECDsa.ExportParameters(includePrivateParameters: false);
 
-                    Debug.Assert(parameters.Q.X != null, SR.GetResourceString(SR.ID5004));
+                    Debug.Assert(parameters.Q.X is not null, SR.GetResourceString(SR.ID5004));
 
                     // Only use the 40 first chars of the base64url-encoded X coordinate.
                     var identifier = Base64UrlEncoder.Encode(parameters.Q.X);

src/OpenIddict.Server/OpenIddictServerDispatcher.cs

@@ -35,7 +35,7 @@ namespace OpenIddict.Server
 
         public async ValueTask DispatchAsync<TContext>(TContext context) where TContext : BaseContext
         {
-            if (context == null)
+            if (context is null)
             {
                 throw new ArgumentNullException(nameof(context));
             }
@@ -103,11 +103,11 @@ namespace OpenIddict.Server
                         continue;
                     }
 
-                    var handler = descriptor.ServiceDescriptor.ImplementationInstance != null ?
+                    var handler = descriptor.ServiceDescriptor.ImplementationInstance is not null ?
                         descriptor.ServiceDescriptor.ImplementationInstance as IOpenIddictServerHandler<TContext> :
                         _provider.GetService(descriptor.ServiceDescriptor.ServiceType) as IOpenIddictServerHandler<TContext>;
 
-                    if (handler == null)
+                    if (handler is null)
                     {
                         throw new InvalidOperationException(SR.FormatID1097(descriptor.ServiceDescriptor.ServiceType));
                     }

src/OpenIddict.Server/OpenIddictServerExtensions.cs

@@ -31,7 +31,7 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictServerBuilder"/>.</returns>
         public static OpenIddictServerBuilder AddServer(this OpenIddictBuilder builder)
         {
-            if (builder == null)
+            if (builder is null)
             {
                 throw new ArgumentNullException(nameof(builder));
             }
@@ -107,12 +107,12 @@ namespace Microsoft.Extensions.DependencyInjection
         /// <returns>The <see cref="OpenIddictBuilder"/>.</returns>
         public static OpenIddictBuilder AddServer(this OpenIddictBuilder builder, Action<OpenIddictServerBuilder> configuration)
         {
-            if (builder == null)
+            if (builder is null)
             {
                 throw new ArgumentNullException(nameof(builder));
             }
 
-            if (configuration == null)
+            if (configuration is null)
             {
                 throw new ArgumentNullException(nameof(configuration));
             }

src/OpenIddict.Server/OpenIddictServerHandlerDescriptor.cs

@@ -79,7 +79,7 @@ namespace OpenIddict.Server
             /// <returns>The builder instance, so that calls can be easily chained.</returns>
             public Builder<TContext> AddFilter(Type type)
             {
-                if (type == null)
+                if (type is null)
                 {
                     throw new ArgumentNullException(nameof(type));
                 }
@@ -110,7 +110,7 @@ namespace OpenIddict.Server
             /// <returns>The builder instance, so that calls can be easily chained.</returns>
             public Builder<TContext> SetServiceDescriptor(ServiceDescriptor descriptor)
             {
-                if (descriptor == null)
+                if (descriptor is null)
                 {
                     throw new ArgumentNullException(nameof(descriptor));
                 }
@@ -162,7 +162,7 @@ namespace OpenIddict.Server
             /// <returns>The builder instance, so that calls can be easily chained.</returns>
             public Builder<TContext> UseInlineHandler(Func<TContext, ValueTask> handler)
             {
-                if (handler == null)
+                if (handler is null)
                 {
                     throw new ArgumentNullException(nameof(handler));
                 }
@@ -199,7 +199,7 @@ namespace OpenIddict.Server
             public Builder<TContext> UseSingletonHandler<THandler>(THandler handler)
                 where THandler : IOpenIddictServerHandler<TContext>
             {
-                if (handler == null)
+                if (handler is null)
                 {
                     throw new ArgumentNullException(nameof(handler));
                 }

src/OpenIddict.Server/OpenIddictServerHandlerFilters.cs

@@ -21,7 +21,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(ProcessSignInContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -37,7 +37,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(ProcessSignInContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -53,7 +53,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -69,7 +69,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -85,7 +85,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -101,7 +101,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -117,7 +117,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -133,7 +133,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -149,7 +149,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(ProcessSignInContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -165,7 +165,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -181,7 +181,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -197,7 +197,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -213,7 +213,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(ProcessSignInContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -229,7 +229,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -245,7 +245,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -261,7 +261,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -277,7 +277,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -293,7 +293,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -309,7 +309,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(ProcessSignInContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -325,7 +325,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -341,7 +341,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -357,7 +357,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -373,7 +373,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -389,7 +389,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -405,7 +405,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -421,7 +421,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -437,7 +437,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -453,7 +453,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(ProcessSignInContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -469,7 +469,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }
@@ -485,7 +485,7 @@ namespace OpenIddict.Server
         {
             public ValueTask<bool> IsActiveAsync(BaseContext context)
             {
-                if (context == null)
+                if (context is null)
                 {
                     throw new ArgumentNullException(nameof(context));
                 }

src/OpenIddict.Server/OpenIddictServerHandlers.Authentication.cs

@@ -88,7 +88,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ProcessRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -117,7 +117,7 @@ namespace OpenIddict.Server
                         return;
                     }
 
-                    if (notification.Request == null)
+                    if (notification.Request is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1026));
                     }
@@ -150,7 +150,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ProcessRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -216,7 +216,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ProcessRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -245,7 +245,7 @@ namespace OpenIddict.Server
                         return;
                     }
 
-                    if (notification.Principal != null)
+                    if (notification.Principal is not null)
                     {
                         var @event = new ProcessSignInContext(context.Transaction)
                         {
@@ -305,7 +305,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(TContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -347,7 +347,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(ValidateAuthorizationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -386,7 +386,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(ValidateAuthorizationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -425,7 +425,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(ValidateAuthorizationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -465,7 +465,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(ValidateAuthorizationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -546,7 +546,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(ValidateAuthorizationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -599,7 +599,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(ValidateAuthorizationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -679,7 +679,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(ValidateAuthorizationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -728,7 +728,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(ValidateAuthorizationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -776,7 +776,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(ValidateAuthorizationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -817,7 +817,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(ValidateAuthorizationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -923,7 +923,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ValidateAuthorizationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -931,7 +931,7 @@ namespace OpenIddict.Server
                     Debug.Assert(!string.IsNullOrEmpty(context.ClientId), SR.FormatID5000(Parameters.ClientId));
 
                     var application = await _applicationManager.FindByClientIdAsync(context.ClientId);
-                    if (application == null)
+                    if (application is null)
                     {
                         context.Logger.LogError(SR.GetResourceString(SR.ID7044), context.ClientId);
 
@@ -972,7 +972,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ValidateAuthorizationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -980,7 +980,7 @@ namespace OpenIddict.Server
                     Debug.Assert(!string.IsNullOrEmpty(context.ClientId), SR.FormatID5000(Parameters.ClientId));
 
                     var application = await _applicationManager.FindByClientIdAsync(context.ClientId);
-                    if (application == null)
+                    if (application is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1031));
                     }
@@ -1030,7 +1030,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ValidateAuthorizationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -1038,7 +1038,7 @@ namespace OpenIddict.Server
                     Debug.Assert(!string.IsNullOrEmpty(context.ClientId), SR.FormatID5000(Parameters.ClientId));
 
                     var application = await _applicationManager.FindByClientIdAsync(context.ClientId);
-                    if (application == null)
+                    if (application is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1031));
                     }
@@ -1107,7 +1107,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ValidateAuthorizationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -1121,7 +1121,7 @@ namespace OpenIddict.Server
                     // even if the service was registered and resolved from the dependency injection container.
                     if (scopes.Count != 0 && !context.Options.EnableDegradedMode)
                     {
-                        Debug.Assert(_scopeManager != null, SR.GetResourceString(SR.ID5011));
+                        Debug.Assert(_scopeManager is not null, SR.GetResourceString(SR.ID5011));
 
                         await foreach (var scope in _scopeManager.FindByNamesAsync(scopes.ToImmutableArray()))
                         {
@@ -1175,7 +1175,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ValidateAuthorizationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -1183,7 +1183,7 @@ namespace OpenIddict.Server
                     Debug.Assert(!string.IsNullOrEmpty(context.ClientId), SR.FormatID5000(Parameters.ClientId));
 
                     var application = await _applicationManager.FindByClientIdAsync(context.ClientId);
-                    if (application == null)
+                    if (application is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1031));
                     }
@@ -1230,7 +1230,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ValidateAuthorizationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -1238,7 +1238,7 @@ namespace OpenIddict.Server
                     Debug.Assert(!string.IsNullOrEmpty(context.ClientId), SR.FormatID5000(Parameters.ClientId));
 
                     var application = await _applicationManager.FindByClientIdAsync(context.ClientId);
-                    if (application == null)
+                    if (application is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1031));
                     }
@@ -1327,7 +1327,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ValidateAuthorizationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -1335,7 +1335,7 @@ namespace OpenIddict.Server
                     Debug.Assert(!string.IsNullOrEmpty(context.ClientId), SR.FormatID5000(Parameters.ClientId));
 
                     var application = await _applicationManager.FindByClientIdAsync(context.ClientId);
-                    if (application == null)
+                    if (application is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1031));
                     }
@@ -1392,7 +1392,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ValidateAuthorizationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -1407,7 +1407,7 @@ namespace OpenIddict.Server
                     }
 
                     var application = await _applicationManager.FindByClientIdAsync(context.ClientId);
-                    if (application == null)
+                    if (application is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1031));
                     }
@@ -1444,12 +1444,12 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(ApplyAuthorizationResponseContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
 
-                    if (context.Request == null)
+                    if (context.Request is null)
                     {
                         return default;
                     }
@@ -1459,7 +1459,7 @@ namespace OpenIddict.Server
 
                     // Note: at this stage, the validated redirect URI property may be null (e.g if an error
                     // is returned from the ExtractAuthorizationRequest/ValidateAuthorizationRequest events).
-                    if (notification != null && !notification.IsRejected)
+                    if (notification is not null && !notification.IsRejected)
                     {
                         context.RedirectUri = notification.RedirectUri;
                     }
@@ -1487,12 +1487,12 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(ApplyAuthorizationResponseContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
 
-                    if (context.Request == null)
+                    if (context.Request is null)
                     {
                         return default;
                     }
@@ -1529,7 +1529,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(ApplyAuthorizationResponseContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }

src/OpenIddict.Server/OpenIddictServerHandlers.Device.cs

@@ -86,7 +86,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ProcessRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -115,7 +115,7 @@ namespace OpenIddict.Server
                         return;
                     }
 
-                    if (notification.Request == null)
+                    if (notification.Request is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1030));
                     }
@@ -148,7 +148,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ProcessRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -205,7 +205,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ProcessRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -234,7 +234,7 @@ namespace OpenIddict.Server
                         return;
                     }
 
-                    if (notification.Principal == null)
+                    if (notification.Principal is null)
                     {
                         // Note: no authentication type is deliberately specified to represent an unauthenticated identity.
                         var principal = new ClaimsPrincipal(new ClaimsIdentity());
@@ -298,7 +298,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(TContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -340,7 +340,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(ValidateDeviceRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -391,7 +391,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ValidateDeviceRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -405,7 +405,7 @@ namespace OpenIddict.Server
                     // even if the service was registered and resolved from the dependency injection container.
                     if (scopes.Count != 0 && !context.Options.EnableDegradedMode)
                     {
-                        Debug.Assert(_scopeManager != null, SR.GetResourceString(SR.ID5011));
+                        Debug.Assert(_scopeManager is not null, SR.GetResourceString(SR.ID5011));
 
                         await foreach (var scope in _scopeManager.FindByNamesAsync(scopes.ToImmutableArray()))
                         {
@@ -459,7 +459,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ValidateDeviceRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -469,7 +469,7 @@ namespace OpenIddict.Server
                     // Retrieve the application details corresponding to the requested client_id.
                     // If no entity can be found, this likely indicates that the client_id is invalid.
                     var application = await _applicationManager.FindByClientIdAsync(context.ClientId);
-                    if (application == null)
+                    if (application is null)
                     {
                         context.Logger.LogError(SR.GetResourceString(SR.ID7058), context.ClientId);
 
@@ -511,7 +511,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ValidateDeviceRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -519,7 +519,7 @@ namespace OpenIddict.Server
                     Debug.Assert(!string.IsNullOrEmpty(context.ClientId), SR.FormatID5000(Parameters.ClientId));
 
                     var application = await _applicationManager.FindByClientIdAsync(context.ClientId);
-                    if (application == null)
+                    if (application is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1031));
                     }
@@ -583,7 +583,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ValidateDeviceRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -591,7 +591,7 @@ namespace OpenIddict.Server
                     Debug.Assert(!string.IsNullOrEmpty(context.ClientId), SR.FormatID5000(Parameters.ClientId));
 
                     var application = await _applicationManager.FindByClientIdAsync(context.ClientId);
-                    if (application == null)
+                    if (application is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1031));
                     }
@@ -647,7 +647,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ValidateDeviceRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -655,7 +655,7 @@ namespace OpenIddict.Server
                     Debug.Assert(!string.IsNullOrEmpty(context.ClientId), SR.FormatID5000(Parameters.ClientId));
 
                     var application = await _applicationManager.FindByClientIdAsync(context.ClientId);
-                    if (application == null)
+                    if (application is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1031));
                     }
@@ -704,7 +704,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ValidateDeviceRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -712,7 +712,7 @@ namespace OpenIddict.Server
                     Debug.Assert(!string.IsNullOrEmpty(context.ClientId), SR.FormatID5000(Parameters.ClientId));
 
                     var application = await _applicationManager.FindByClientIdAsync(context.ClientId);
-                    if (application == null)
+                    if (application is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1031));
                     }
@@ -765,7 +765,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ProcessRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -794,7 +794,7 @@ namespace OpenIddict.Server
                         return;
                     }
 
-                    if (notification.Request == null)
+                    if (notification.Request is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1033));
                     }
@@ -827,7 +827,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ProcessRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -884,7 +884,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ProcessRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -913,7 +913,7 @@ namespace OpenIddict.Server
                         return;
                     }
 
-                    if (notification.Principal != null)
+                    if (notification.Principal is not null)
                     {
                         var @event = new ProcessSignInContext(context.Transaction)
                         {
@@ -973,7 +973,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(TContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -1020,7 +1020,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(HandleVerificationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }

src/OpenIddict.Server/OpenIddictServerHandlers.Discovery.cs

@@ -90,7 +90,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ProcessRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -119,7 +119,7 @@ namespace OpenIddict.Server
                         return;
                     }
 
-                    if (notification.Request == null)
+                    if (notification.Request is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1036));
                     }
@@ -152,7 +152,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ProcessRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -209,7 +209,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ProcessRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -295,7 +295,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(TContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -337,7 +337,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(HandleConfigurationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -374,7 +374,7 @@ namespace OpenIddict.Server
                     static Uri? GetEndpointAbsoluteUri(Uri? issuer, Uri endpoint)
                     {
                         // If the endpoint is disabled (i.e a null address is specified), return null.
-                        if (endpoint == null)
+                        if (endpoint is null)
                         {
                             return null;
                         }
@@ -386,7 +386,7 @@ namespace OpenIddict.Server
                         }
 
                         // At this stage, throw an exception if the issuer cannot be retrieved.
-                        if (issuer == null || !issuer.IsAbsoluteUri)
+                        if (issuer is null || !issuer.IsAbsoluteUri)
                         {
                             throw new InvalidOperationException(SR.GetResourceString(SR.ID1022));
                         }
@@ -428,7 +428,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(HandleConfigurationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -457,7 +457,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(HandleConfigurationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -486,7 +486,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(HandleConfigurationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -516,24 +516,24 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(HandleConfigurationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
 
-                    if (context.IntrospectionEndpoint != null)
+                    if (context.IntrospectionEndpoint is not null)
                     {
                         context.IntrospectionEndpointAuthenticationMethods.Add(ClientAuthenticationMethods.ClientSecretBasic);
                         context.IntrospectionEndpointAuthenticationMethods.Add(ClientAuthenticationMethods.ClientSecretPost);
                     }
 
-                    if (context.RevocationEndpoint != null)
+                    if (context.RevocationEndpoint is not null)
                     {
                         context.RevocationEndpointAuthenticationMethods.Add(ClientAuthenticationMethods.ClientSecretBasic);
                         context.RevocationEndpointAuthenticationMethods.Add(ClientAuthenticationMethods.ClientSecretPost);
                     }
 
-                    if (context.TokenEndpoint != null)
+                    if (context.TokenEndpoint is not null)
                     {
                         context.TokenEndpointAuthenticationMethods.Add(ClientAuthenticationMethods.ClientSecretBasic);
                         context.TokenEndpointAuthenticationMethods.Add(ClientAuthenticationMethods.ClientSecretPost);
@@ -562,7 +562,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(HandleConfigurationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -591,7 +591,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(HandleConfigurationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -620,7 +620,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(HandleConfigurationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -649,7 +649,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(HandleConfigurationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -678,7 +678,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(HandleConfigurationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -744,7 +744,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(HandleConfigurationRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -783,7 +783,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ProcessRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -812,7 +812,7 @@ namespace OpenIddict.Server
                         return;
                     }
 
-                    if (notification.Request == null)
+                    if (notification.Request is null)
                     {
                         throw new InvalidOperationException(SR.GetResourceString(SR.ID1037));
                     }
@@ -845,7 +845,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ProcessRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -902,7 +902,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(ProcessRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -1030,7 +1030,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public async ValueTask HandleAsync(TContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -1072,7 +1072,7 @@ namespace OpenIddict.Server
                 /// <inheritdoc/>
                 public ValueTask HandleAsync(HandleCryptographyRequestContext context)
                 {
-                    if (context == null)
+                    if (context is null)
                     {
                         throw new ArgumentNullException(nameof(context));
                     }
@@ -1149,7 +1149,7 @@ namespace OpenIddict.Server
                                 X509SecurityKey x509SecurityKey when x509SecurityKey.PublicKey is RSA algorithm =>
                                     algorithm.ExportParameters(includePrivateParameters: false),
 
-                                RsaSecurityKey rsaSecurityKey when rsaSecurityKey.Rsa != null =>
+                                RsaSecurityKey rsaSecurityKey when rsaSecurityKey.Rsa is not null =>
                                     rsaSecurityKey.Rsa.ExportParameters(includePrivateParameters: false),
 
                                 RsaSecurityKey rsaSecurityKey => rsaSecurityKey.Parameters,
@@ -1157,15 +1157,15 @@ namespace OpenIddict.Server
                                 _ => (RSAParameters?) null
                             };
 
-                            if (parameters == null)
+                            if (parameters is null)
                             {
                                 context.Logger.LogWarning(SR.GetResourceString(SR.ID7073), credentials.Key.GetType().Name);
 
                                 continue;
                             }
 
-                            Debug.Assert(parameters.Value.Exponent != null &&
-                                         parameters.Value.Modulus != null, SR.GetResourceString(SR.ID5003));
+                            Debug.Assert(parameters.Value.Exponent is not null &&
+                                         parameters.Value.Modulus is not null, SR.GetResourceString(SR.ID5003));
 
                             key.Kty = JsonWebAlgorithmsKeyTypes.RSA;
 
@@ -1185,21 +1185,21 @@ namespace OpenIddict.Server
                                 X509SecurityKey x509SecurityKey when x509SecurityKey.PublicKey is ECDsa algorithm =>
                                     algorithm.ExportParameters(includePrivateParameters: false),
 
-                                ECDsaSecurityKey ecdsaSecurityKey when ecdsaSecurityKey.ECDsa != null =>
+                                ECDsaSecurityKey ecdsaSecurityKey when ecdsaSecurityKey.ECDsa is not null =>
                                     ecdsaSecurityKey.ECDsa.ExportParameters(includePrivateParameters: false),
 
                                 _ => (ECParameters?) null
                             };
 
-                            if (parameters == null)
+                            if (parameters is null)
                             {
                                 context.Logger.LogWarning(SR.GetResourceString(SR.ID7074), credentials.Key.GetType().Name);
 
                                 continue;
                             }
 
-                            Debug.Assert(parameters.Value.Q.X != null &&
-                                         parameters.Value.Q.Y != null, SR.GetResourceString(SR.ID5004));
+                            Debug.Assert(parameters.Value.Q.X is not null &&
+                                         parameters.Value.Q.Y is not null, SR.GetResourceString(SR.ID5004));
 
                             Debug.Assert(parameters.Value.Curve.IsNamed, SR.GetResourceString(SR.ID5005));
 
@@ -1218,7 +1218,7 @@ namespace OpenIddict.Server
                         // If the signing key is embedded in a X.509 certificate, set
                         // the x5t and x5c parameters using the certificate details.
                         var certificate = (credentials.Key as X509SecurityKey)?.Certificate;
-                        if (certificate != null)
+                        if (certificate is not null)
                         {
                             // x5t must be base64url-encoded.
                             // See https://tools.ietf.org/html/rfc7517#section-4.8
@@ -1250,7 +1250,7 @@ namespace OpenIddict.Server
                         return certificate.GetCertHash(algorithm);
 #else
                         using var hash = CryptoConfig.CreateFromName(algorithm.Name) as HashAlgorithm;
-                        if (hash == null || hash is KeyedHashAlgorithm)
+                        if (hash is null || hash is KeyedHashAlgorithm)
                         {
                             throw new InvalidOperationException(SR.GetResourceString(SR.ID1216));
                         }