Polyfill ValueTask.CompletedTask and ValueTask<TResult>.CompletedTask

Directory.Build.props

@@ -3,7 +3,7 @@
   <Import Project="Sdk.props" Sdk="Microsoft.DotNet.Arcade.Sdk" />
 
   <PropertyGroup>
-    <LangVersion>13.0</LangVersion>
+    <LangVersion>14.0</LangVersion>
     <EnableNETAnalyzers>true</EnableNETAnalyzers>
     <AnalysisLevel>9.0</AnalysisLevel>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
@@ -218,6 +218,7 @@
 
   <ItemGroup Condition=" '$(IncludeInternalExtensions)' == 'true' ">
     <Compile Include="$(MSBuildThisFileDirectory)shared\OpenIddict.Extensions\*.cs" Visible="false" />
+    <Using Include="OpenIddict.Extensions" />
   </ItemGroup>
 
 </Project>

Directory.Build.targets

@@ -58,6 +58,7 @@
     <DefineConstants>$(DefineConstants);SUPPORTS_AUTHORIZATION_MIDDLEWARE</DefineConstants>
     <DefineConstants>$(DefineConstants);SUPPORTS_BCL_ASYNC_ENUMERABLE</DefineConstants>
     <DefineConstants>$(DefineConstants);SUPPORTS_BULK_DBSET_OPERATIONS</DefineConstants>
+    <DefineConstants>$(DefineConstants);SUPPORTS_CHUNK_LINQ_EXTENSION</DefineConstants>
     <DefineConstants>$(DefineConstants);SUPPORTS_DBSET_VALUETASK_FINDASYNC</DefineConstants>
     <DefineConstants>$(DefineConstants);SUPPORTS_ENDPOINT_ROUTING</DefineConstants>
     <DefineConstants>$(DefineConstants);SUPPORTS_ENVIRONMENT_PROCESS_PATH</DefineConstants>
@@ -77,6 +78,7 @@
     <DefineConstants>$(DefineConstants);SUPPORTS_TASK_WAIT_ASYNC</DefineConstants>
     <DefineConstants>$(DefineConstants);SUPPORTS_TEXT_ELEMENT_ENUMERATOR</DefineConstants>
     <DefineConstants>$(DefineConstants);SUPPORTS_TIME_PROVIDER</DefineConstants>
+    <DefineConstants>$(DefineConstants);SUPPORTS_VALUETASK_COMPLETED_TASK</DefineConstants>
     <DefineConstants>$(DefineConstants);SUPPORTS_WINFORMS_TASK_DIALOG</DefineConstants>
     <DefineConstants>$(DefineConstants);SUPPORTS_ZLIB_COMPRESSION</DefineConstants>
   </PropertyGroup>

sandbox/OpenIddict.Sandbox.AspNet.Server/Startup.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Globalization;
 using System.Threading.Tasks;
 using System.Web.Http;
 using System.Web.Mvc;

shared/OpenIddict.Extensions/OpenIddictHelpers.cs

@@ -23,36 +23,6 @@ namespace OpenIddict.Extensions;
 /// </summary>
 internal static class OpenIddictHelpers
 {
-    /// <summary>
-    /// Generates a sequence of non-overlapping adjacent buffers over the source sequence.
-    /// </summary>
-    /// <typeparam name="TSource">The source sequence element type.</typeparam>
-    /// <param name="source">The source sequence.</param>
-    /// <param name="count">The number of elements for allocated buffers.</param>
-    /// <returns>A sequence of buffers containing source sequence elements.</returns>
-    public static IEnumerable<List<TSource>> Buffer<TSource>(this IEnumerable<TSource> source, int count)
-    {
-        List<TSource>? buffer = null;
-
-        foreach (var element in source)
-        {
-            buffer ??= [];
-            buffer.Add(element);
-
-            if (buffer.Count == count)
-            {
-                yield return buffer;
-
-                buffer = null;
-            }
-        }
-
-        if (buffer is not null)
-        {
-            yield return buffer;
-        }
-    }
-
     /// <summary>
     /// Determines whether the specified array contains at least one value present in the specified set.
     /// </summary>
@@ -82,54 +52,6 @@ internal static class OpenIddictHelpers
         return false;
     }
 
-#if !SUPPORTS_TASK_WAIT_ASYNC
-    /// <summary>
-    /// Waits until the specified task returns a result or the cancellation token is signaled.
-    /// </summary>
-    /// <param name="task">The task.</param>
-    /// <param name="cancellationToken">The <see cref="CancellationToken"/> that can be used to abort the operation.</param>
-    /// <returns>
-    /// A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
-    /// <exception cref="OperationCanceledException">The specified <paramref name="cancellationToken"/> is signaled.</exception>
-    public static async Task WaitAsync(this Task task, CancellationToken cancellationToken)
-    {
-        var source = new TaskCompletionSource<bool>(TaskCreationOptions.None);
-
-        using (cancellationToken.Register(static state => ((TaskCompletionSource<bool>) state!).SetResult(true), source))
-        {
-            if (await Task.WhenAny(task, source.Task) == source.Task)
-            {
-                throw new OperationCanceledException(cancellationToken);
-            }
-
-            await task;
-        }
-    }
-
-    /// <summary>
-    /// Waits until the specified task returns a result or the cancellation token is signaled.
-    /// </summary>
-    /// <param name="task">The task.</param>
-    /// <param name="cancellationToken">The <see cref="CancellationToken"/> that can be used to abort the operation.</param>
-    /// <returns>
-    /// A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
-    /// <exception cref="OperationCanceledException">The specified <paramref name="cancellationToken"/> is signaled.</exception>
-    public static async Task<T> WaitAsync<T>(this Task<T> task, CancellationToken cancellationToken)
-    {
-        var source = new TaskCompletionSource<bool>(TaskCreationOptions.None);
-
-        using (cancellationToken.Register(static state => ((TaskCompletionSource<bool>) state!).SetResult(true), source))
-        {
-            if (await Task.WhenAny(task, source.Task) == source.Task)
-            {
-                throw new OperationCanceledException(cancellationToken);
-            }
-
-            return await task;
-        }
-    }
-#endif
-
     /// <summary>
     /// Determines whether the specified <paramref name="exception"/> is considered fatal.
     /// </summary>
@@ -166,19 +88,6 @@ internal static class OpenIddictHelpers
         }
     }
 
-#if !SUPPORTS_TOHASHSET_LINQ_EXTENSION
-    /// <summary>
-    /// Creates a new <see cref="HashSet{T}"/> instance and imports the elements present in the specified source.
-    /// </summary>
-    /// <typeparam name="TSource">The type of the elements present in the collection.</typeparam>
-    /// <param name="source">The source collection.</param>
-    /// <param name="comparer">The comparer to use.</param>
-    /// <returns>A new <see cref="HashSet{T}"/> instance and imports the elements present in the specified source.</returns>
-    /// <exception cref="ArgumentNullException">The <paramref name="source"/> is <see langword="null"/>.</exception>
-    public static HashSet<TSource> ToHashSet<TSource>(this IEnumerable<TSource> source, IEqualityComparer<TSource>? comparer)
-        => new(source ?? throw new ArgumentNullException(nameof(source)), comparer);
-#endif
-
     /// <summary>
     /// Computes an absolute URI from the specified <paramref name="left"/> and <paramref name="right"/> URIs.
     /// Note: if the <paramref name="right"/> URI is already absolute, it is directly returned.

shared/OpenIddict.Extensions/OpenIddictPolyfills.cs

@@ -0,0 +1,170 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (http://www.apache.org/licenses/LICENSE-2.0)
+ * See https://github.com/openiddict/openiddict-core for more information concerning
+ * the license and the contributors participating to this project.
+ */
+
+using System.Diagnostics;
+
+namespace OpenIddict.Extensions;
+
+/// <summary>
+/// Exposes common polyfills used by the OpenIddict assemblies.
+/// </summary>
+internal static class OpenIddictPolyfills
+{
+    extension<TSource>(IEnumerable<TSource> source)
+    {
+#if !SUPPORTS_CHUNK_LINQ_EXTENSION
+        /// <summary>
+        /// Split the elements of a sequence into chunks of size at most <paramref name="size"/>.
+        /// </summary>
+        /// <remarks>
+        /// Every chunk except the last will be of size <paramref name="size"/>.
+        /// The last chunk will contain the remaining elements and may be of a smaller size.
+        /// </remarks>
+        /// <param name="size">Maximum size of each chunk.</param>
+        /// <returns>
+        /// An <see cref="IEnumerable{T}"/> that contains the elements of the input
+        /// sequence split into chunks of size <paramref name="size"/>.
+        /// </returns>
+        public IEnumerable<TSource[]> Chunk(int size)
+        {
+            // Note: this polyfill was directly copied from .NET's source code:
+            // https://github.com/dotnet/runtime/blob/main/src/libraries/System.Linq/src/System/Linq/Chunk.cs.
+
+            using IEnumerator<TSource> enumerator = source.GetEnumerator();
+
+            if (enumerator.MoveNext())
+            {
+                var count = Math.Min(size, 4);
+                int index;
+
+                do
+                {
+                    var array = new TSource[count];
+
+                    array[0] = enumerator.Current;
+                    index = 1;
+
+                    if (size != array.Length)
+                    {
+                        for (; index < size && enumerator.MoveNext(); index++)
+                        {
+                            if (index >= array.Length)
+                            {
+                                count = (int) Math.Min((uint) size, 2 * (uint) array.Length);
+                                Array.Resize(ref array, count);
+                            }
+
+                            array[index] = enumerator.Current;
+                        }
+                    }
+
+                    else
+                    {
+                        var local = array;
+                        Debug.Assert(local.Length == size);
+                        for (; (uint) index < (uint) local.Length && enumerator.MoveNext(); index++)
+                        {
+                            local[index] = enumerator.Current;
+                        }
+                    }
+
+                    if (index != array.Length)
+                    {
+                        Array.Resize(ref array, index);
+                    }
+
+                    yield return array;
+                }
+
+                while (index >= size && enumerator.MoveNext());
+            }
+        }
+#endif
+
+#if !SUPPORTS_TOHASHSET_LINQ_EXTENSION
+        /// <summary>
+        /// Creates a new <see cref="HashSet{T}"/> instance and imports the elements present in the specified source.
+        /// </summary>
+        /// <param name="comparer">The comparer to use.</param>
+        /// <returns>A new <see cref="HashSet{T}"/> instance and imports the elements present in the specified source.</returns>
+        public HashSet<TSource> ToHashSet(IEqualityComparer<TSource>? comparer) => new(source, comparer);
+#endif
+    }
+
+    extension(Task task)
+    {
+#if !SUPPORTS_TASK_WAIT_ASYNC
+        /// <summary>
+        /// Waits until the specified task returns a result or the cancellation token is signaled.
+        /// </summary>
+        /// <param name="cancellationToken">The <see cref="CancellationToken"/> that can be used to abort the operation.</param>
+        /// <returns>
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <exception cref="OperationCanceledException">The specified <paramref name="cancellationToken"/> is signaled.</exception>
+        public async Task WaitAsync(CancellationToken cancellationToken)
+        {
+            var source = new TaskCompletionSource<bool>(TaskCreationOptions.None);
+
+            using (cancellationToken.Register(static state => ((TaskCompletionSource<bool>) state!).SetResult(true), source))
+            {
+                if (await Task.WhenAny(task, source.Task) == source.Task)
+                {
+                    throw new OperationCanceledException(cancellationToken);
+                }
+
+                await task;
+            }
+        }
+#endif
+    }
+
+    extension<TResult>(Task<TResult> task)
+    {
+#if !SUPPORTS_TASK_WAIT_ASYNC
+        /// <summary>
+        /// Waits until the specified task returns a result or the cancellation token is signaled.
+        /// </summary>
+        /// <param name="cancellationToken">The <see cref="CancellationToken"/> that can be used to abort the operation.</param>
+        /// <returns>
+        /// A <see cref="Task"/> that can be used to monitor the asynchronous operation.</returns>
+        /// <exception cref="OperationCanceledException">The specified <paramref name="cancellationToken"/> is signaled.</exception>
+        public async Task<TResult> WaitAsync(CancellationToken cancellationToken)
+        {
+            var source = new TaskCompletionSource<bool>(TaskCreationOptions.None);
+
+            using (cancellationToken.Register(static state => ((TaskCompletionSource<bool>) state!).SetResult(true), source))
+            {
+                if (await Task.WhenAny(task, source.Task) == source.Task)
+                {
+                    throw new OperationCanceledException(cancellationToken);
+                }
+
+                return await task;
+            }
+        }
+#endif
+    }
+
+    extension(ValueTask)
+    {
+#if !SUPPORTS_VALUETASK_COMPLETED_TASK
+        /// <summary>
+        /// Gets a task that has already completed successfully.
+        /// </summary>
+        public static ValueTask CompletedTask => default;
+#endif
+    }
+
+    extension<TResult>(ValueTask<TResult>)
+    {
+#if !SUPPORTS_VALUETASK_COMPLETED_TASK
+        /// <summary>
+        /// Gets a task that has already completed successfully.
+        /// </summary>
+        public static ValueTask<TResult> CompletedTask => default;
+#endif
+    }
+}

src/OpenIddict.Abstractions/Primitives/OpenIddictExtensions.cs

@@ -14,7 +14,6 @@ using System.Text.Encodings.Web;
 using System.Text.Json;
 using System.Text.Json.Nodes;
 using Microsoft.Extensions.Primitives;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Abstractions;
 

src/OpenIddict.Abstractions/Primitives/OpenIddictParameter.cs

@@ -12,7 +12,6 @@ using System.Runtime.InteropServices;
 using System.Text.Json;
 using System.Text.Json.Nodes;
 using Microsoft.Extensions.Primitives;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Abstractions;
 

src/OpenIddict.Client.AspNetCore/OpenIddictClientAspNetCoreHandlers.Authentication.cs

@@ -100,7 +100,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
                 response.Redirect(location);
                 context.HandleRequest();
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Client.AspNetCore/OpenIddictClientAspNetCoreHandlers.Session.cs

@@ -100,7 +100,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
                 response.Redirect(location);
                 context.HandleRequest();
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Client.AspNetCore/OpenIddictClientAspNetCoreHandlers.cs

@@ -20,7 +20,6 @@ using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Microsoft.IdentityModel.Tokens;
 using Microsoft.Net.Http.Headers;
-using OpenIddict.Extensions;
 using Properties = OpenIddict.Client.AspNetCore.OpenIddictClientAspNetCoreConstants.Properties;
 
 namespace OpenIddict.Client.AspNetCore;
@@ -120,7 +119,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
             context.BaseUri = CreateUri(UriHelper.BuildAbsolute(request.Scheme, host, request.PathBase));
             context.RequestUri = CreateUri(UriHelper.BuildAbsolute(request.Scheme, host, request.PathBase, request.Path, request.QueryString));
 
-            return default;
+            return ValueTask.CompletedTask;
 
             // Note: the BCL System.Uri class has strict rules (e.g it rejects specific characters and enforces a
             // limit of 65519 characters for the complete URI representation). To ensure no exception is thrown if the
@@ -168,10 +167,10 @@ public static partial class OpenIddictClientAspNetCoreHandlers
                     description: SR.GetResourceString(SR.ID2083),
                     uri: SR.FormatID8000(SR.ID2083));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -213,10 +212,10 @@ public static partial class OpenIddictClientAspNetCoreHandlers
                     description: SR.FormatID2081(HeaderNames.Host),
                     uri: SR.FormatID8000(SR.ID2081));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -330,7 +329,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0402));
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -364,7 +363,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0377));
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -437,7 +436,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
                     description: SR.GetResourceString(SR.ID2129),
                     uri: SR.FormatID8000(SR.ID2129));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             try
@@ -451,7 +450,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
                         description: SR.GetResourceString(SR.ID2163),
                         uri: SR.FormatID8000(SR.ID2163));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Extract the length of the request forgery protection.
@@ -463,7 +462,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
                         description: SR.GetResourceString(SR.ID2163),
                         uri: SR.FormatID8000(SR.ID2163));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Note: since the correlation cookie is not protected against tampering, an unexpected
@@ -480,7 +479,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
                     description: SR.GetResourceString(SR.ID2163),
                     uri: SR.FormatID8000(SR.ID2163));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Return a response header asking the browser to delete the state cookie.
@@ -488,7 +487,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
             // Note: when deleting a cookie, the same options used when creating it MUST be specified.
             request.HttpContext.Response.Cookies.Delete(name, builder.Build(request.HttpContext));
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -522,7 +521,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0402));
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -629,7 +628,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
                 }
             }
 
-            return default;
+            return ValueTask.CompletedTask;
 
             static string? GetProperty(AuthenticationProperties properties, string name)
                 => properties.Items.TryGetValue(name, out string? value) ? value : null;
@@ -672,7 +671,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0364));
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -704,7 +703,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
             // If an explicit response type was specified, don't overwrite it.
             if (!string.IsNullOrEmpty(context.ResponseMode))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Note: in most cases, the query response mode will be used as it offers the best compatibility and,
@@ -715,7 +714,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
             // the remote server, the response types are taken into account when selecting the best response mode.
             if (context.ResponseType?.Split(Separators.Space) is not IList<string> { Count: > 0 } types)
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             context.ResponseMode = (
@@ -764,7 +763,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
                 _ => null
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -857,7 +856,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
             // Add the correlation cookie to the response headers.
             response.Cookies.Append(name, Base64UrlEncoder.Encode(payload), options);
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -954,7 +953,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
                 }
             }
 
-            return default;
+            return ValueTask.CompletedTask;
 
             static string? GetProperty(AuthenticationProperties properties, string name)
                 => properties.Items.TryGetValue(name, out string? value) ? value : null;
@@ -997,7 +996,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0365));
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1089,7 +1088,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
             // Add the correlation cookie to the response headers.
             response.Cookies.Append(name, Base64UrlEncoder.Encode(payload), options);
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1123,7 +1122,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
 
             context.SkipRequest();
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1166,7 +1165,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
                 _ => 400
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1205,7 +1204,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
             response.Headers[HeaderNames.Pragma] = "no-cache";
             response.Headers[HeaderNames.Expires] = "Thu, 01 Jan 1970 00:00:00 GMT";
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1243,12 +1242,12 @@ public static partial class OpenIddictClientAspNetCoreHandlers
 
             if (string.IsNullOrEmpty(context.Transaction.Response.Error))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             context.SkipRequest();
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1288,7 +1287,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
 
             if (string.IsNullOrEmpty(context.Transaction.Response.Error))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Determine if the status code pages middleware has been enabled for this request.
@@ -1297,7 +1296,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
             var feature = response.HttpContext.Features.Get<IStatusCodePagesFeature>();
             if (feature is not { Enabled: true })
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Mark the request as fully handled to prevent the other OpenIddict client handlers
@@ -1305,7 +1304,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
             // to rewrite the response using the logic defined by the developer when registering it.
             context.HandleRequest();
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1412,7 +1411,7 @@ public static partial class OpenIddictClientAspNetCoreHandlers
             context.Logger.LogInformation(6145, SR.GetResourceString(SR.ID6145));
             context.HandleRequest();
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 }

src/OpenIddict.Client.DataProtection/OpenIddictClientDataProtectionHandlers.Protection.cs

@@ -10,7 +10,6 @@ using Microsoft.AspNetCore.DataProtection;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Microsoft.IdentityModel.Tokens;
-using OpenIddict.Extensions;
 using static OpenIddict.Client.DataProtection.OpenIddictClientDataProtectionConstants.Purposes;
 using static OpenIddict.Client.OpenIddictClientHandlers.Protection;
 using Schemes = OpenIddict.Client.DataProtection.OpenIddictClientDataProtectionConstants.Purposes.Schemes;
@@ -61,13 +60,13 @@ public static partial class OpenIddictClientDataProtectionHandlers
                 // If a principal was already attached, don't overwrite it.
                 if (context.Principal is not null)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // If a specific token format is expected, return immediately if it doesn't match the expected value.
                 if (context.TokenFormat is not null and not TokenFormats.Private.DataProtection)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Note: ASP.NET Core Data Protection tokens created by the default implementation always start
@@ -84,7 +83,7 @@ public static partial class OpenIddictClientDataProtectionHandlers
                         "Microsoft.AspNetCore.DataProtection.KeyManagement.KeyRingBasedDataProtectionProvider",
                         StringComparison.Ordinal))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Note: unlike the equivalent handler in the server stack, the logic used here
@@ -108,14 +107,14 @@ public static partial class OpenIddictClientDataProtectionHandlers
                         description: SR.GetResourceString(SR.ID2004),
                         uri: SR.FormatID8000(SR.ID2004));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 context.Principal = principal;
 
                 context.Logger.LogTrace(6152, SR.GetResourceString(SR.ID6152), context.Token, context.Principal.Claims);
 
-                return default;
+                return ValueTask.CompletedTask;
 
                 ClaimsPrincipal? ValidateToken(string type)
                 {
@@ -196,7 +195,7 @@ public static partial class OpenIddictClientDataProtectionHandlers
                     _ => context.TokenFormat // Don't override the format if the token type is not supported.
                 };
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -232,7 +231,7 @@ public static partial class OpenIddictClientDataProtectionHandlers
                 // If an access token was already attached by another handler, don't overwrite it.
                 if (!string.IsNullOrEmpty(context.Token))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Create a Data Protection protector using the provider registered in the options.
@@ -259,7 +258,7 @@ public static partial class OpenIddictClientDataProtectionHandlers
                 context.Logger.LogTrace(6016, SR.GetResourceString(SR.ID6016), context.TokenType,
                     context.Token, context.Principal.Claims);
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Client.Owin/OpenIddictClientOwinHandlers.Authentication.cs

@@ -90,7 +90,7 @@ public static partial class OpenIddictClientOwinHandlers
                 response.Redirect(location);
                 context.HandleRequest();
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Client.Owin/OpenIddictClientOwinHandlers.Session.cs

@@ -88,7 +88,7 @@ public static partial class OpenIddictClientOwinHandlers
                 response.Redirect(location);
                 context.HandleRequest();
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Client.Owin/OpenIddictClientOwinHandlers.cs

@@ -16,7 +16,6 @@ using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Microsoft.Extensions.Primitives;
 using Microsoft.IdentityModel.Tokens;
-using OpenIddict.Extensions;
 using Owin;
 using static OpenIddict.Client.Owin.OpenIddictClientOwinConstants;
 using Properties = OpenIddict.Client.Owin.OpenIddictClientOwinConstants.Properties;
@@ -117,7 +116,7 @@ public static partial class OpenIddictClientOwinHandlers
             context.BaseUri = CreateUri(request.Scheme + Uri.SchemeDelimiter + host + request.PathBase);
             context.RequestUri = CreateUri(request.Scheme + Uri.SchemeDelimiter + host + request.PathBase + request.Path + request.QueryString);
 
-            return default;
+            return ValueTask.CompletedTask;
 
             // Note: the BCL System.Uri class has strict rules (e.g it rejects specific characters and enforces a
             // limit of 65519 characters for the complete URI representation). To ensure no exception is thrown if the
@@ -160,7 +159,7 @@ public static partial class OpenIddictClientOwinHandlers
             // Don't require that transport security be used if the request is not handled by OpenIddict.
             if (context.EndpointType is OpenIddictClientEndpointType.Unknown)
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             if (!request.IsSecure)
@@ -170,10 +169,10 @@ public static partial class OpenIddictClientOwinHandlers
                     description: SR.GetResourceString(SR.ID2083),
                     uri: SR.FormatID8000(SR.ID2083));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -216,10 +215,10 @@ public static partial class OpenIddictClientOwinHandlers
                     description: SR.FormatID2081(Headers.Host),
                     uri: SR.FormatID8000(SR.ID2081));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -339,7 +338,7 @@ public static partial class OpenIddictClientOwinHandlers
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0402));
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -373,7 +372,7 @@ public static partial class OpenIddictClientOwinHandlers
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0377));
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -448,7 +447,7 @@ public static partial class OpenIddictClientOwinHandlers
                     description: SR.GetResourceString(SR.ID2129),
                     uri: SR.FormatID8000(SR.ID2129));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             try
@@ -462,7 +461,7 @@ public static partial class OpenIddictClientOwinHandlers
                         description: SR.GetResourceString(SR.ID2163),
                         uri: SR.FormatID8000(SR.ID2163));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Extract the length of the request forgery protection.
@@ -474,7 +473,7 @@ public static partial class OpenIddictClientOwinHandlers
                         description: SR.GetResourceString(SR.ID2163),
                         uri: SR.FormatID8000(SR.ID2163));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Note: since the correlation cookie is not protected against tampering, an unexpected
@@ -491,7 +490,7 @@ public static partial class OpenIddictClientOwinHandlers
                     description: SR.GetResourceString(SR.ID2163),
                     uri: SR.FormatID8000(SR.ID2163));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Return a response header asking the browser to delete the state cookie.
@@ -506,7 +505,7 @@ public static partial class OpenIddictClientOwinHandlers
                 Secure = options.Secure
             });
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -540,7 +539,7 @@ public static partial class OpenIddictClientOwinHandlers
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0402));
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -578,7 +577,7 @@ public static partial class OpenIddictClientOwinHandlers
             var properties = context.Transaction.GetProperty<AuthenticationProperties>(typeof(AuthenticationProperties).FullName!);
             if (properties is not { Dictionary.Count: > 0 })
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             context.CodeChallengeMethod = GetProperty(properties, Properties.CodeChallengeMethod);
@@ -660,7 +659,7 @@ public static partial class OpenIddictClientOwinHandlers
                 }
             }
 
-            return default;
+            return ValueTask.CompletedTask;
 
             static string? GetProperty(AuthenticationProperties properties, string name)
                 => properties.Dictionary.TryGetValue(name, out string? value) ? value : null;
@@ -703,7 +702,7 @@ public static partial class OpenIddictClientOwinHandlers
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0364));
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -735,7 +734,7 @@ public static partial class OpenIddictClientOwinHandlers
             // If an explicit response type was specified, don't overwrite it.
             if (!string.IsNullOrEmpty(context.ResponseMode))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Note: in most cases, the query response mode will be used as it offers the best compatibility and,
@@ -746,7 +745,7 @@ public static partial class OpenIddictClientOwinHandlers
             // the remote server, the response types are taken into account when selecting the best response mode.
             if (context.ResponseType?.Split(Separators.Space) is not IList<string> { Count: > 0 } types)
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             context.ResponseMode = (
@@ -795,7 +794,7 @@ public static partial class OpenIddictClientOwinHandlers
                 _ => null
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -896,7 +895,7 @@ public static partial class OpenIddictClientOwinHandlers
                 Expires = context.StateTokenPrincipal.GetExpirationDate()?.UtcDateTime
             });
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -934,7 +933,7 @@ public static partial class OpenIddictClientOwinHandlers
             var properties = context.Transaction.GetProperty<AuthenticationProperties>(typeof(AuthenticationProperties).FullName!);
             if (properties is not { Dictionary.Count: > 0 })
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             context.IdentityTokenHint = GetProperty(properties, Properties.IdentityTokenHint);
@@ -1006,7 +1005,7 @@ public static partial class OpenIddictClientOwinHandlers
                 }
             }
 
-            return default;
+            return ValueTask.CompletedTask;
 
             static string? GetProperty(AuthenticationProperties properties, string name)
                 => properties.Dictionary.TryGetValue(name, out string? value) ? value : null;
@@ -1049,7 +1048,7 @@ public static partial class OpenIddictClientOwinHandlers
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0365));
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1149,7 +1148,7 @@ public static partial class OpenIddictClientOwinHandlers
                 Expires = context.StateTokenPrincipal.GetExpirationDate()?.UtcDateTime
             });
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1183,7 +1182,7 @@ public static partial class OpenIddictClientOwinHandlers
 
             context.SkipRequest();
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1226,7 +1225,7 @@ public static partial class OpenIddictClientOwinHandlers
                 _ => 400
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1279,7 +1278,7 @@ public static partial class OpenIddictClientOwinHandlers
                     properties         : response.Context.Authentication.AuthenticationResponseChallenge?.Properties ?? new());
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1324,7 +1323,7 @@ public static partial class OpenIddictClientOwinHandlers
                 TrySuppressFormsAuthenticationRedirect(response.Environment);
             }
 
-            return default;
+            return ValueTask.CompletedTask;
 
             static void TrySuppressFormsAuthenticationRedirect(IDictionary<string, object> environment)
             {
@@ -1385,7 +1384,7 @@ public static partial class OpenIddictClientOwinHandlers
             response.Headers[Headers.Pragma] = "no-cache";
             response.Headers[Headers.Expires] = "Thu, 01 Jan 1970 00:00:00 GMT";
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1423,12 +1422,12 @@ public static partial class OpenIddictClientOwinHandlers
 
             if (string.IsNullOrEmpty(context.Transaction.Response.Error))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             context.SkipRequest();
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1535,7 +1534,7 @@ public static partial class OpenIddictClientOwinHandlers
             context.Logger.LogInformation(6145, SR.GetResourceString(SR.ID6145));
             context.HandleRequest();
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 }

src/OpenIddict.Client.SystemIntegration/OpenIddictClientSystemIntegrationActivation.cs

@@ -5,7 +5,6 @@
  */
 
 using System.ComponentModel;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Client.SystemIntegration;
 

src/OpenIddict.Client.SystemIntegration/OpenIddictClientSystemIntegrationConfiguration.cs

@@ -14,7 +14,6 @@ using System.Text;
 using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Options;
 using Microsoft.IdentityModel.Tokens;
-using OpenIddict.Extensions;
 using static OpenIddict.Client.SystemIntegration.OpenIddictClientSystemIntegrationAuthenticationMode;
 
 namespace OpenIddict.Client.SystemIntegration;

src/OpenIddict.Client.SystemIntegration/OpenIddictClientSystemIntegrationHandlers.Authentication.cs

@@ -9,7 +9,6 @@ using System.Runtime.InteropServices;
 using System.Runtime.Versioning;
 using System.Text;
 using Microsoft.Extensions.Primitives;
-using OpenIddict.Extensions;
 
 #if SUPPORTS_ANDROID
 using Android.Content;

src/OpenIddict.Client.SystemIntegration/OpenIddictClientSystemIntegrationHandlers.Session.cs

@@ -9,7 +9,6 @@ using System.Runtime.InteropServices;
 using System.Runtime.Versioning;
 using System.Text;
 using Microsoft.Extensions.Primitives;
-using OpenIddict.Extensions;
 
 #if SUPPORTS_ANDROID
 using Android.Content;

src/OpenIddict.Client.SystemIntegration/OpenIddictClientSystemIntegrationHandlers.cs

@@ -16,7 +16,6 @@ using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Microsoft.Extensions.Primitives;
 using Microsoft.Net.Http.Headers;
-using OpenIddict.Extensions;
 using static OpenIddict.Client.SystemIntegration.OpenIddictClientSystemIntegrationConstants;
 
 namespace OpenIddict.Client.SystemIntegration;
@@ -154,7 +153,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 _ => throw new InvalidOperationException(SR.GetResourceString(SR.ID0390))
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -192,7 +191,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 _ => throw new InvalidOperationException(SR.GetResourceString(SR.ID0375))
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -230,7 +229,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 _ => throw new InvalidOperationException(SR.GetResourceString(SR.ID0393))
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -263,13 +262,13 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
             // If the base or request URIs couldn't be resolved, don't try to infer the endpoint type.
             if (context is not { BaseUri.IsAbsoluteUri: true, RequestUri.IsAbsoluteUri: true })
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // If an endpoint was already inferred by the generic handler, don't override it.
             if (context.EndpointType is not OpenIddictClientEndpointType.Unknown)
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             context.EndpointType =
@@ -277,7 +276,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 Matches(context.Options.PostLogoutRedirectionEndpointUris) ? OpenIddictClientEndpointType.PostLogoutRedirection :
                                                                              OpenIddictClientEndpointType.Unknown;
 
-            return default;
+            return ValueTask.CompletedTask;
 
             bool Matches(IReadOnlyList<Uri> uris)
             {
@@ -351,10 +350,10 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 response.StatusCode = (int) HttpStatusCode.NotFound;
 
                 context.HandleRequest();
-                return default;
+                return ValueTask.CompletedTask;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -398,7 +397,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                     description: SR.GetResourceString(SR.ID2084),
                     uri: SR.FormatID8000(SR.ID2084));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             context.Transaction.Request = request.QueryString.AllKeys.Length switch
@@ -407,7 +406,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 _ => new OpenIddictRequest(request.QueryString)
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -555,7 +554,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
 
             context.Transaction.Request = new OpenIddictRequest(parameters);
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -591,7 +590,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
 
             context.Transaction.Request = new OpenIddictRequest(callback.Parameters);
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -739,7 +738,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 _ => (context.Configuration, context.Registration)
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -785,7 +784,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 _ => context.StateToken
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -832,7 +831,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 _ => context.StateTokenPrincipal
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -879,7 +878,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 }
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1020,12 +1019,12 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                     description: SR.GetResourceString(SR.ID2139),
                     uri: SR.FormatID8000(SR.ID2139));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             context.RequestForgeryProtection = protection;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1073,7 +1072,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 _ => (context.AuthorizationCode, context.FrontchannelAccessToken, context.FrontchannelIdentityToken)
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1120,7 +1119,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 _ => context.FrontchannelIdentityTokenPrincipal
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1167,7 +1166,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 _ => context.FrontchannelAccessTokenPrincipal
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1214,7 +1213,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 _ => context.AuthorizationCodePrincipal
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1260,7 +1259,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 _ => context.TokenResponse
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1308,7 +1307,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 _ => (context.BackchannelAccessToken, context.BackchannelIdentityToken, context.RefreshToken)
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1355,7 +1354,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 _ => context.BackchannelIdentityTokenPrincipal
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1402,7 +1401,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 _ => context.BackchannelAccessTokenPrincipal
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1449,7 +1448,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 _ => context.RefreshTokenPrincipal
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1495,7 +1494,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 _ => (context.UserInfoResponse, context.UserInfoTokenPrincipal, context.UserInfoToken)
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1540,7 +1539,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 _ => context.MergedPrincipal
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1583,7 +1582,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0380));
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1626,7 +1625,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0381));
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1657,7 +1656,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
 
             context.BaseUri ??= context.Options.ClientUri;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1947,7 +1946,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
             // should be redirected to a different instance using inter-process communication.
             context.StateTokenPrincipal.SetClaim(Claims.Private.InstanceId, _options.CurrentValue.InstanceIdentifier);
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1997,7 +1996,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0378));
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -2028,7 +2027,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
 
             context.BaseUri ??= context.Options.ClientUri;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -2129,7 +2128,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
             // should be redirected to a different instance using inter-process communication.
             context.StateTokenPrincipal.SetClaim(Claims.Private.InstanceId, _options.CurrentValue.InstanceIdentifier);
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -2179,7 +2178,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0378));
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -2236,10 +2235,10 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 _lifetime.StopApplication();
 
                 context.HandleRequest();
-                return default;
+                return ValueTask.CompletedTask;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -2282,7 +2281,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
                 _ => 400
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -2321,7 +2320,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
             response.Headers[Headers.Pragma] = "no-cache";
             response.Headers[Headers.Expires] = "Thu, 01 Jan 1970 00:00:00 GMT";
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -2358,7 +2357,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
             // Note: this logic applies to both successful and errored responses.
 
             context.HandleRequest();
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -2394,7 +2393,7 @@ public static partial class OpenIddictClientSystemIntegrationHandlers
             // Note: this logic applies to both successful and errored responses.
 
             context.HandleRequest();
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 }

src/OpenIddict.Client.SystemIntegration/OpenIddictClientSystemIntegrationHelpers.cs

@@ -12,7 +12,6 @@ using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using System.Runtime.Versioning;
 using System.Security.Principal;
-using OpenIddict.Extensions;
 
 #if SUPPORTS_ANDROID
 using Android.Content;

src/OpenIddict.Client.SystemIntegration/OpenIddictClientSystemIntegrationHttpListener.cs

@@ -12,7 +12,6 @@ using System.Runtime.InteropServices;
 using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Client.SystemIntegration;
 

src/OpenIddict.Client.SystemIntegration/OpenIddictClientSystemIntegrationMarshal.cs

@@ -7,7 +7,6 @@
 using System.Collections.Concurrent;
 using System.ComponentModel;
 using System.Diagnostics.CodeAnalysis;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Client.SystemIntegration;
 

src/OpenIddict.Client.SystemIntegration/OpenIddictClientSystemIntegrationPipeListener.cs

@@ -10,7 +10,6 @@ using System.Runtime.InteropServices;
 using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Client.SystemIntegration;
 

src/OpenIddict.Client.SystemIntegration/OpenIddictClientSystemIntegrationPlatformCallback.cs

@@ -6,7 +6,6 @@
 
 using System.Collections.Immutable;
 using System.ComponentModel;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Client.SystemIntegration;
 

src/OpenIddict.Client.SystemNetHttp/OpenIddictClientSystemNetHttpHandlers.Userinfo.cs

@@ -80,7 +80,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
                 // Remove the access token from the request payload to ensure it's not sent twice.
                 context.Request.AccessToken = null;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 

src/OpenIddict.Client.SystemNetHttp/OpenIddictClientSystemNetHttpHandlers.cs

@@ -16,7 +16,6 @@ using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Microsoft.Extensions.Primitives;
 using Microsoft.IdentityModel.Tokens;
-using OpenIddict.Extensions;
 using static OpenIddict.Client.SystemNetHttp.OpenIddictClientSystemNetHttpConstants;
 
 namespace OpenIddict.Client.SystemNetHttp;
@@ -91,7 +90,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
             // If an explicit client authentication method was attached, don't overwrite it.
             if (!string.IsNullOrEmpty(context.TokenEndpointClientAuthenticationMethod))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             context.TokenEndpointClientAuthenticationMethod = (
@@ -175,7 +174,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
                 _ => null
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -225,7 +224,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
                (context.Configuration.MtlsUserInfoEndpoint ?? context.Configuration.UserInfoEndpoint) is not Uri endpoint ||
                !string.Equals(endpoint.Scheme, Uri.UriSchemeHttps, StringComparison.OrdinalIgnoreCase))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             if (context.TokenEndpointClientAuthenticationMethod is ClientAuthenticationMethods.TlsClientAuth &&
@@ -240,7 +239,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
                 context.UserInfoEndpointTokenBindingMethods.Add(TokenBindingMethods.Private.SelfSignedTlsClientCertificate);
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -278,7 +277,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
             // If an explicit client authentication method was attached, don't overwrite it.
             if (!string.IsNullOrEmpty(context.DeviceAuthorizationEndpointClientAuthenticationMethod))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             context.DeviceAuthorizationEndpointClientAuthenticationMethod = (
@@ -370,7 +369,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
                 _ => null
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -408,7 +407,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
             // If an explicit client authentication method was attached, don't overwrite it.
             if (!string.IsNullOrEmpty(context.PushedAuthorizationEndpointClientAuthenticationMethod))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             context.PushedAuthorizationEndpointClientAuthenticationMethod = (
@@ -501,7 +500,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
                 _ => null
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -539,7 +538,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
             // If an explicit client authentication method was attached, don't overwrite it.
             if (!string.IsNullOrEmpty(context.IntrospectionEndpointClientAuthenticationMethod))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             context.IntrospectionEndpointClientAuthenticationMethod = (
@@ -623,7 +622,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
                 _ => null
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -661,7 +660,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
             // If an explicit client authentication method was attached, don't overwrite it.
             if (!string.IsNullOrEmpty(context.RevocationEndpointClientAuthenticationMethod))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             context.RevocationEndpointClientAuthenticationMethod = (
@@ -745,7 +744,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
                 _ => null
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -834,7 +833,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
             context.Transaction.SetProperty(typeof(HttpClient).FullName!, _factory.CreateClient(builder.ToString()) ??
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0174)));
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -866,7 +865,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
             context.Transaction.SetProperty(typeof(HttpRequestMessage).FullName!,
                 new HttpRequestMessage(HttpMethod.Get, context.RemoteUri));
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -898,7 +897,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
             context.Transaction.SetProperty(typeof(HttpRequestMessage).FullName!,
                 new HttpRequestMessage(HttpMethod.Post, context.RemoteUri));
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -945,7 +944,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
             request.VersionPolicy = client.DefaultVersionPolicy;
 #endif
 #endif
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -986,7 +985,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
             // that require using HTTP compression can register a custom event handler to send an
             // Accept-Encoding header containing the supported algorithms (e.g GZip/Deflate/Brotli).
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1040,7 +1039,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
                 productName: assembly.Name!,
                 productVersion: assembly.Version!.ToString()));
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1081,7 +1080,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
             // Attach the contact address specified in the options, if available.
             request.Headers.From = _options.CurrentValue.ContactAddress?.ToString();
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1135,7 +1134,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
                 context.Transaction.Request.ClientId = context.Transaction.Request.ClientSecret = null;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
 
             static string? EscapeDataString(string? value)
                 => value is not null ? Uri.EscapeDataString(value).Replace("%20", "+") : null;
@@ -1175,7 +1174,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
 
             if (context.Transaction.Request.Count is 0)
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // For GET requests, attach the request parameters to the query string by default.
@@ -1198,7 +1197,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
                     select new KeyValuePair<string?, string?>(parameter.Key, value));
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1300,7 +1299,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
             // Remove the request from the transaction properties.
             context.Transaction.SetProperty<HttpRequestMessage>(typeof(HttpRequestMessage).FullName!, null);
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1556,7 +1555,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
             // Don't overwrite the response if one was already provided.
             if (context.Transaction.Response is not null)
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // This handler only applies to System.Net.Http requests. If the HTTP response cannot be resolved,
@@ -1566,14 +1565,14 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
 
             if (response.Headers.WwwAuthenticate.Count is 0)
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             context.Transaction.Response = new OpenIddictResponse(response.Headers.WwwAuthenticate
                 .Where(static header => !string.IsNullOrEmpty(header.Parameter))
                 .SelectMany(static header => ParseParameters(header.Parameter!)));
 
-            return default;
+            return ValueTask.CompletedTask;
 
             static IEnumerable<KeyValuePair<string, string?>> ParseParameters(string parameter)
             {
@@ -1685,7 +1684,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
             // Don't overwrite the response if one was already provided.
             if (context.Transaction.Response is not null)
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // This handler only applies to System.Net.Http requests. If the HTTP response cannot be resolved,
@@ -1700,7 +1699,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
                 context.Transaction.Response = new OpenIddictResponse();
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1808,7 +1807,7 @@ public static partial class OpenIddictClientSystemNetHttpHandlers
             // Remove the response from the transaction properties.
             context.Transaction.SetProperty<HttpResponseMessage>(typeof(HttpResponseMessage).FullName!, null);
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 }

src/OpenIddict.Client.WebIntegration/OpenIddictClientWebIntegrationHandlers.Authentication.cs

@@ -57,7 +57,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                     context.Request.ResponseType = null;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Client.WebIntegration/OpenIddictClientWebIntegrationHandlers.Device.cs

@@ -6,7 +6,6 @@
 
 using System.Collections.Immutable;
 using System.Text.Json;
-using OpenIddict.Extensions;
 using static OpenIddict.Client.WebIntegration.OpenIddictClientWebIntegrationConstants;
 
 namespace OpenIddict.Client.WebIntegration;
@@ -49,7 +48,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
 
                 if (context.Response is null)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Note: Google doesn't return a standard "verification_uri" parameter
@@ -91,7 +90,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                     context.Response["expire_in"] = null;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Client.WebIntegration/OpenIddictClientWebIntegrationHandlers.Discovery.cs

@@ -5,7 +5,6 @@
  */
 
 using System.Collections.Immutable;
-using OpenIddict.Extensions;
 using static OpenIddict.Client.OpenIddictClientHandlers.Discovery;
 using static OpenIddict.Client.WebIntegration.OpenIddictClientWebIntegrationConstants;
 
@@ -76,7 +75,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                     _ => context.Response[Metadata.Issuer]
                 };
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -160,7 +159,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                     context.Configuration.GrantTypesSupported.Add(GrantTypes.RefreshToken);
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -206,7 +205,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                     context.Configuration.CodeChallengeMethodsSupported.Add(CodeChallengeMethods.Sha256);
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -258,7 +257,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                     context.Configuration.ScopesSupported.Add(Scopes.OpenId);
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -373,7 +372,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                         ClientAuthenticationMethods.PrivateKeyJwt);
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -453,7 +452,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                         new Uri("https://api-m.sandbox.paypal.com/v1/oauth2/token/userinfo", UriKind.Absolute);
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Client.WebIntegration/OpenIddictClientWebIntegrationHandlers.Exchange.cs

@@ -13,7 +13,6 @@ using System.Net.Http.Json;
 using System.Text;
 using System.Text.Json;
 using Microsoft.Extensions.Primitives;
-using OpenIddict.Extensions;
 using static OpenIddict.Client.SystemNetHttp.OpenIddictClientSystemNetHttpConstants;
 using static OpenIddict.Client.SystemNetHttp.OpenIddictClientSystemNetHttpHandlerFilters;
 using static OpenIddict.Client.SystemNetHttp.OpenIddictClientSystemNetHttpHandlers;
@@ -115,7 +114,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                     context.Request.RedirectUri = null;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -176,7 +175,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                     context.Request.ClientId = context.Request.ClientSecret = null;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -228,7 +227,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                     context.Request.ClientId = null;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -264,7 +263,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
 
                 if (request.RequestUri is null)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // By default, Deezer returns non-standard token responses formatted as formurl-encoded
@@ -290,7 +289,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                         });
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -340,7 +339,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                     _ => request.Content
                 };
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -370,7 +369,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
 
                 if (context.Response is null)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Note: when using the client credentials grant, Dailymotion returns a "refresh_token"
@@ -433,7 +432,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                     context.Response["id_token"] = null;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Client.WebIntegration/OpenIddictClientWebIntegrationHandlers.Introspection.cs

@@ -6,7 +6,6 @@
 
 using System.Collections.Immutable;
 using System.Text.Json;
-using OpenIddict.Extensions;
 using static OpenIddict.Client.WebIntegration.OpenIddictClientWebIntegrationConstants;
 
 namespace OpenIddict.Client.WebIntegration;
@@ -49,7 +48,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
 
                 if (context.Response is null)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Note: NetSuite returns the "scope" parameter as a non-standard JSON array of strings,
@@ -73,7 +72,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                     context.Response.Scope = string.Join(" ", scopes);
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Client.WebIntegration/OpenIddictClientWebIntegrationHandlers.Protection.cs

@@ -54,7 +54,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 // In this case, don't amend the default token validation parameters.
                 if (context.Registration is null)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 context.TokenValidationParameters.ValidateIssuer = context.Registration.ProviderType switch
@@ -81,7 +81,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                     _ => context.TokenValidationParameters.ValidateIssuer
                 };
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -112,7 +112,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 // In this case, don't amend the default security token descriptor.
                 if (context.Registration is null)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 context.SecurityTokenDescriptor.TokenType = context.Registration.ProviderType switch
@@ -130,7 +130,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                     _ => context.SecurityTokenDescriptor.TokenType
                 };
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Client.WebIntegration/OpenIddictClientWebIntegrationHandlers.Revocation.cs

@@ -82,7 +82,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                     _ => request.Content
                 };
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -144,7 +144,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                     context.Request.ClientSecret = null;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -184,7 +184,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                     _ => request.Method
                 };
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -236,7 +236,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                     request.Headers.Authorization = new AuthenticationHeaderValue(Schemes.Bearer, token);
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -272,7 +272,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
 
                 if (response.Content is null)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Some providers are known to return invalid or incorrect media types, which prevents
@@ -296,7 +296,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                     _ => response.Content.Headers.ContentType
                 };
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Client.WebIntegration/OpenIddictClientWebIntegrationHandlers.Userinfo.cs

@@ -82,7 +82,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                     _ => request.Method
                 };
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -145,7 +145,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                     request.Headers.Add("Client-ID", context.Registration.ClientId);
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -210,7 +210,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                         request.Headers.Authorization?.Parameter);
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -251,7 +251,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                     context.Request.ClientId = context.Registration.ClientId;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -301,7 +301,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                     _ => request.Content
                 };
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -337,7 +337,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
 
                 if (response.Content is null)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Some providers are known to return invalid or incorrect media types, which prevents
@@ -367,7 +367,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                     _ => response.Content.Headers.ContentType
                 };
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -488,7 +488,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                     _ => context.Response
                 };
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -536,7 +536,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Client.WebIntegration/OpenIddictClientWebIntegrationHandlers.cs

@@ -10,7 +10,6 @@ using System.Diagnostics;
 using System.Security.Claims;
 using System.Text;
 using System.Text.Json;
-using OpenIddict.Extensions;
 using static OpenIddict.Client.WebIntegration.OpenIddictClientWebIntegrationConstants;
 
 namespace OpenIddict.Client.WebIntegration;
@@ -114,7 +113,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                         description: SR.FormatID2029("hmac"),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 var builder = new StringBuilder();
@@ -162,7 +161,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                             description: SR.FormatID2052("hmac"),
                             uri: SR.FormatID8000(SR.ID2052));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
                 }
 
@@ -173,11 +172,11 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                         description: SR.FormatID2052("hmac"),
                         uri: SR.FormatID8000(SR.ID2052));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -237,7 +236,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                            _   => SR.FormatID8000(SR.ID2152)
                     });
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             else if (context.Registration.ProviderType is ProviderTypes.Deezer)
@@ -266,7 +265,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                                   _       => SR.FormatID8000(SR.ID2152)
                         });
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
             }
 
@@ -292,7 +291,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                               _  => SR.FormatID8000(SR.ID2152)
                         });
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
             }
 
@@ -307,7 +306,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                         description: SR.GetResourceString(SR.ID2149),
                         uri: SR.FormatID8000(SR.ID2149));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
             }
 
@@ -321,11 +320,11 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                         description: SR.GetResourceString(SR.ID2149),
                         uri: SR.FormatID8000(SR.ID2149));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -367,7 +366,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                         description: SR.FormatID2029("shop"),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Resolve the shop name from the authentication properties.
@@ -389,7 +388,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                         description: SR.FormatID2052("shop"),
                         uri: SR.FormatID8000(SR.ID2052));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
             }
 
@@ -404,7 +403,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                         description: SR.FormatID2029("device_id"),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Store the device identifier as an authentication property
@@ -424,7 +423,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                         description: SR.FormatID2029("location"),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Ensure the specified location corresponds to well-known region.
@@ -435,7 +434,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                         description: SR.FormatID2052("location"),
                         uri: SR.FormatID8000(SR.ID2052));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Store the validated location as an authentication property
@@ -443,7 +442,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 context.Properties[Zoho.Properties.Location] = location;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -487,7 +486,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 _ => context.TokenEndpointClientAuthenticationMethod
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -573,7 +572,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 _ => context.TokenEndpoint
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -618,7 +617,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 context.ClientAssertionPrincipal.SetAudiences("https://appleid.apple.com");
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -684,7 +683,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 };
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -729,7 +728,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 context.TokenRequest.ClientAssertionType = null;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -762,7 +761,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
 
             if (context.TokenRequest.RedirectUri is null)
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Note: some providers don't support the "state" parameter, don't flow
@@ -788,7 +787,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 _ => context.TokenRequest.RedirectUri
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -838,7 +837,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                       context.ValidateBackchannelIdentityToken)
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -884,7 +883,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 _ => context.DisableBackchannelIdentityTokenNonceValidation
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -975,7 +974,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 _ => context.SendUserInfoRequest
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1015,7 +1014,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 _ => context.DisableUserInfoValidation
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1108,7 +1107,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 _ => context.UserInfoEndpoint
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1244,7 +1243,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 context.UserInfoRequest["uid"] = context.TokenResponse?["uid"];
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1279,7 +1278,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
             // Don't overwrite the userinfo token principal if one was already set.
             if (context.UserInfoTokenPrincipal is not null)
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Some providers don't provide an OAuth 2.0/OpenID Connect userinfo endpoint but
@@ -1311,7 +1310,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
 
             if (parameters is null)
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             var identity = new ClaimsIdentity(
@@ -1349,7 +1348,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
 
             context.UserInfoTokenPrincipal = new ClaimsPrincipal(identity);
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1615,7 +1614,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 _ => context.MergedPrincipal.GetClaim(ClaimTypes.NameIdentifier)
             });
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1657,7 +1656,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 context.Properties[Shopify.Properties.ShopName] = settings.ShopName;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1733,7 +1732,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 _ => context.AuthorizationEndpoint
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1770,7 +1769,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 _ => context.ResponseMode
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1814,7 +1813,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 _ => context.Request.Scope
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1845,7 +1844,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
 
             if (context.RedirectUri is null)
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Note: some providers don't support the "state" parameter, don't flow
@@ -1868,7 +1867,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 context.Request.State = null;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -2061,7 +2060,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 context.Request.Prompt = settings.Prompt;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -2099,7 +2098,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 _ => context.RevocationEndpointClientAuthenticationMethod
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -2144,7 +2143,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 context.ClientAssertionPrincipal.SetAudiences("https://appleid.apple.com");
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -2189,7 +2188,7 @@ public static partial class OpenIddictClientWebIntegrationHandlers
                 context.RevocationRequest.ClientAssertionType = null;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 }

src/OpenIddict.Client/OpenIddictClientBuilder.cs

@@ -14,7 +14,6 @@ using System.Security.Cryptography.X509Certificates;
 using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.IdentityModel.Tokens;
 using OpenIddict.Client;
-using OpenIddict.Extensions;
 
 namespace Microsoft.Extensions.DependencyInjection;
 

src/OpenIddict.Client/OpenIddictClientConfiguration.cs

@@ -14,7 +14,6 @@ using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Options;
 using Microsoft.IdentityModel.Protocols;
 using Microsoft.IdentityModel.Tokens;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Client;
 

src/OpenIddict.Client/OpenIddictClientDispatcher.cs

@@ -7,7 +7,6 @@
 using System.ComponentModel;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Client;
 

src/OpenIddict.Client/OpenIddictClientHandlers.Authentication.cs

@@ -7,7 +7,6 @@
 using System.Collections.Immutable;
 using System.Text.Json;
 using Microsoft.Extensions.Logging;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Client;
 
@@ -187,7 +186,7 @@ public static partial class OpenIddictClientHandlers
                 // Don't overwrite the endpoint URI if it was already set.
                 if (!string.IsNullOrEmpty(context.AuthorizationEndpoint))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Ensure the authorization endpoint is present and is a valid absolute URI.
@@ -199,7 +198,7 @@ public static partial class OpenIddictClientHandlers
 
                 context.AuthorizationEndpoint = context.Configuration.AuthorizationEndpoint.AbsoluteUri;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -235,11 +234,11 @@ public static partial class OpenIddictClientHandlers
                             description: SR.FormatID2107(parameter.Key),
                             uri: SR.FormatID8000(SR.ID2107));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
 
                 // Note: in the typical case, the response parameters should be deserialized from a
                 // JSON response and thus natively stored as System.Text.Json.JsonElement instances.
@@ -307,10 +306,10 @@ public static partial class OpenIddictClientHandlers
                         description: SR.GetResourceString(SR.ID2179),
                         uri: SR.FormatID8000(SR.ID2179));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -347,7 +346,7 @@ public static partial class OpenIddictClientHandlers
                         description: SR.FormatID2180(Parameters.RequestUri),
                         uri: SR.FormatID8000(SR.ID2180));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Return an error if the "request_uri" parameter is malformed.
@@ -359,10 +358,10 @@ public static partial class OpenIddictClientHandlers
                         description: SR.FormatID2181(Parameters.RequestUri),
                         uri: SR.FormatID8000(SR.ID2181));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -400,10 +399,10 @@ public static partial class OpenIddictClientHandlers
                         description: SR.FormatID2180(Parameters.ExpiresIn),
                         uri: SR.FormatID8000(SR.ID2180));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -670,7 +669,7 @@ public static partial class OpenIddictClientHandlers
                     context.Request.ResponseMode = null;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 

src/OpenIddict.Client/OpenIddictClientHandlers.Device.cs

@@ -7,7 +7,6 @@
 using System.Collections.Immutable;
 using System.Text.Json;
 using Microsoft.Extensions.Logging;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Client;
 
@@ -58,11 +57,11 @@ public static partial class OpenIddictClientHandlers
                             description: SR.FormatID2107(parameter.Key),
                             uri: SR.FormatID8000(SR.ID2107));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
 
                 // Note: in the typical case, the response parameters should be deserialized from a
                 // JSON response and thus natively stored as System.Text.Json.JsonElement instances.
@@ -136,10 +135,10 @@ public static partial class OpenIddictClientHandlers
                         description: SR.GetResourceString(SR.ID2167),
                         uri: SR.FormatID8000(SR.ID2167));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -176,7 +175,7 @@ public static partial class OpenIddictClientHandlers
                         description: SR.FormatID2168(Parameters.VerificationUri),
                         uri: SR.FormatID8000(SR.ID2168));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Return an error if the "verification_uri" parameter is malformed.
@@ -188,7 +187,7 @@ public static partial class OpenIddictClientHandlers
                         description: SR.FormatID2169(Parameters.VerificationUri),
                         uri: SR.FormatID8000(SR.ID2169));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Note: the "verification_uri_complete" parameter is optional and MUST NOT
@@ -202,10 +201,10 @@ public static partial class OpenIddictClientHandlers
                         description: SR.FormatID2169(Parameters.VerificationUriComplete),
                         uri: SR.FormatID8000(SR.ID2169));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -242,10 +241,10 @@ public static partial class OpenIddictClientHandlers
                         description: SR.FormatID2168(Parameters.ExpiresIn),
                         uri: SR.FormatID8000(SR.ID2168));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Client/OpenIddictClientHandlers.Discovery.cs

@@ -8,7 +8,6 @@ using System.Collections.Immutable;
 using System.Text.Json;
 using Microsoft.Extensions.Logging;
 using Microsoft.IdentityModel.Tokens;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Client;
 
@@ -93,11 +92,11 @@ public static partial class OpenIddictClientHandlers
                             description: SR.FormatID2107(parameter.Key),
                             uri: SR.FormatID8000(SR.ID2107));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
 
                 // Note: in the typical case, the response parameters should be deserialized from a
                 // JSON response and thus natively stored as System.Text.Json.JsonElement instances.
@@ -190,10 +189,10 @@ public static partial class OpenIddictClientHandlers
                         description: SR.GetResourceString(SR.ID2144),
                         uri: SR.FormatID8000(SR.ID2144));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -231,7 +230,7 @@ public static partial class OpenIddictClientHandlers
                         description: SR.GetResourceString(SR.ID2096),
                         uri: SR.FormatID8000(SR.ID2096));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 if (!Uri.TryCreate(issuer, UriKind.Absolute, out Uri? uri))
@@ -241,7 +240,7 @@ public static partial class OpenIddictClientHandlers
                         description: SR.GetResourceString(SR.ID2097),
                         uri: SR.FormatID8000(SR.ID2097));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Ensure the issuer matches the expected value.
@@ -252,12 +251,12 @@ public static partial class OpenIddictClientHandlers
                         description: SR.GetResourceString(SR.ID2165),
                         uri: SR.FormatID8000(SR.ID2165));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 context.Configuration.Issuer = uri;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -303,13 +302,13 @@ public static partial class OpenIddictClientHandlers
                             description: SR.FormatID2100(Metadata.AuthorizationEndpoint),
                             uri: SR.FormatID8000(SR.ID2100));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
 
                     context.Configuration.AuthorizationEndpoint = uri;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -346,7 +345,7 @@ public static partial class OpenIddictClientHandlers
                         description: SR.GetResourceString(SR.ID2099),
                         uri: SR.FormatID8000(SR.ID2099));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 if (!Uri.TryCreate(endpoint, UriKind.Absolute, out Uri? uri) || OpenIddictHelpers.IsImplicitFileUri(uri))
@@ -356,12 +355,12 @@ public static partial class OpenIddictClientHandlers
                         description: SR.FormatID2100(Metadata.JwksUri),
                         uri: SR.FormatID8000(SR.ID2100));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 context.Configuration.JsonWebKeySetUri = uri;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -398,13 +397,13 @@ public static partial class OpenIddictClientHandlers
                             description: SR.FormatID2100(Metadata.DeviceAuthorizationEndpoint),
                             uri: SR.FormatID8000(SR.ID2100));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
 
                     context.Configuration.DeviceAuthorizationEndpoint = uri;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -441,13 +440,13 @@ public static partial class OpenIddictClientHandlers
                             description: SR.FormatID2100(Metadata.IntrospectionEndpoint),
                             uri: SR.FormatID8000(SR.ID2100));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
 
                     context.Configuration.IntrospectionEndpoint = uri;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -484,13 +483,13 @@ public static partial class OpenIddictClientHandlers
                             description: SR.FormatID2100(Metadata.EndSessionEndpoint),
                             uri: SR.FormatID8000(SR.ID2100));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
 
                     context.Configuration.EndSessionEndpoint = uri;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -526,7 +525,7 @@ public static partial class OpenIddictClientHandlers
                     context.Configuration.MtlsDeviceAuthorizationEndpoint = uri;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -562,7 +561,7 @@ public static partial class OpenIddictClientHandlers
                     context.Configuration.MtlsIntrospectionEndpoint = uri;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -597,7 +596,7 @@ public static partial class OpenIddictClientHandlers
                     context.Configuration.MtlsPushedAuthorizationEndpoint = uri;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -632,7 +631,7 @@ public static partial class OpenIddictClientHandlers
                     context.Configuration.MtlsRevocationEndpoint = uri;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -667,7 +666,7 @@ public static partial class OpenIddictClientHandlers
                     context.Configuration.MtlsTokenEndpoint = uri;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -702,7 +701,7 @@ public static partial class OpenIddictClientHandlers
                     context.Configuration.MtlsUserInfoEndpoint = uri;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -739,13 +738,13 @@ public static partial class OpenIddictClientHandlers
                             description: SR.FormatID2100(Metadata.PushedAuthorizationRequestEndpoint),
                             uri: SR.FormatID8000(SR.ID2100));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
 
                     context.Configuration.PushedAuthorizationEndpoint = uri;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -782,13 +781,13 @@ public static partial class OpenIddictClientHandlers
                             description: SR.FormatID2100(Metadata.RevocationEndpoint),
                             uri: SR.FormatID8000(SR.ID2100));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
 
                     context.Configuration.RevocationEndpoint = uri;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -825,13 +824,13 @@ public static partial class OpenIddictClientHandlers
                             description: SR.FormatID2100(Metadata.TokenEndpoint),
                             uri: SR.FormatID8000(SR.ID2100));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
 
                     context.Configuration.TokenEndpoint = uri;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -868,13 +867,13 @@ public static partial class OpenIddictClientHandlers
                             description: SR.FormatID2100(Metadata.UserInfoEndpoint),
                             uri: SR.FormatID8000(SR.ID2100));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
 
                     context.Configuration.UserInfoEndpoint = uri;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -910,7 +909,7 @@ public static partial class OpenIddictClientHandlers
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -946,7 +945,7 @@ public static partial class OpenIddictClientHandlers
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -982,7 +981,7 @@ public static partial class OpenIddictClientHandlers
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1018,7 +1017,7 @@ public static partial class OpenIddictClientHandlers
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1054,7 +1053,7 @@ public static partial class OpenIddictClientHandlers
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1085,7 +1084,7 @@ public static partial class OpenIddictClientHandlers
                 context.Configuration.AuthorizationResponseIssParameterSupported = (bool?)
                     context.Response[Metadata.AuthorizationResponseIssParameterSupported];
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1116,7 +1115,7 @@ public static partial class OpenIddictClientHandlers
                 context.Configuration.TlsClientCertificateBoundAccessTokens = (bool?)
                     context.Response[Metadata.TlsClientCertificateBoundAccessTokens];
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1147,7 +1146,7 @@ public static partial class OpenIddictClientHandlers
                 context.Configuration.RequirePushedAuthorizationRequests = (bool?)
                     context.Response[Metadata.RequirePushedAuthorizationRequests];
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1187,7 +1186,7 @@ public static partial class OpenIddictClientHandlers
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1224,7 +1223,7 @@ public static partial class OpenIddictClientHandlers
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1264,7 +1263,7 @@ public static partial class OpenIddictClientHandlers
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1301,7 +1300,7 @@ public static partial class OpenIddictClientHandlers
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1338,7 +1337,7 @@ public static partial class OpenIddictClientHandlers
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1374,11 +1373,11 @@ public static partial class OpenIddictClientHandlers
                             description: SR.FormatID2107(parameter.Key),
                             uri: SR.FormatID8000(SR.ID2107));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
 
                 // Note: in the typical case, the response parameters should be deserialized from a
                 // JSON response and thus natively stored as System.Text.Json.JsonElement instances.
@@ -1440,10 +1439,10 @@ public static partial class OpenIddictClientHandlers
                         description: SR.GetResourceString(SR.ID2145),
                         uri: SR.FormatID8000(SR.ID2145));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1478,7 +1477,7 @@ public static partial class OpenIddictClientHandlers
                         description: SR.FormatID2102(JsonWebKeySetParameterNames.Keys),
                         uri: SR.FormatID8000(SR.ID2102));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 for (var index = 0; index < keys.Count; index++)
@@ -1529,7 +1528,7 @@ public static partial class OpenIddictClientHandlers
                             description: SR.GetResourceString(SR.ID2103),
                             uri: SR.FormatID8000(SR.ID2103));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
 
                     // If the key is a RSA key, ensure the mandatory parameters are all present.
@@ -1541,7 +1540,7 @@ public static partial class OpenIddictClientHandlers
                             description: SR.GetResourceString(SR.ID2104),
                             uri: SR.FormatID8000(SR.ID2104));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
 
                     // If the key is an EC key, ensure the mandatory parameters are all present.
@@ -1553,7 +1552,7 @@ public static partial class OpenIddictClientHandlers
                             description: SR.GetResourceString(SR.ID2104),
                             uri: SR.FormatID8000(SR.ID2104));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
 
                     key.KeyId = (string?) keys[index][JsonWebKeyParameterNames.Kid];
@@ -1576,7 +1575,7 @@ public static partial class OpenIddictClientHandlers
                     context.JsonWebKeySet.Keys.Add(key);
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Client/OpenIddictClientHandlers.Exchange.cs

@@ -55,11 +55,11 @@ public static partial class OpenIddictClientHandlers
                             description: SR.FormatID2107(parameter.Key),
                             uri: SR.FormatID8000(SR.ID2107));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
 
                 // Note: in the typical case, the response parameters should be deserialized from a
                 // JSON response and thus natively stored as System.Text.Json.JsonElement instances.
@@ -135,10 +135,10 @@ public static partial class OpenIddictClientHandlers
                         description: SR.GetResourceString(SR.ID2147),
                         uri: SR.FormatID8000(SR.ID2147));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Client/OpenIddictClientHandlers.Introspection.cs

@@ -10,7 +10,6 @@ using System.Globalization;
 using System.Security.Claims;
 using System.Text.Json;
 using Microsoft.Extensions.Logging;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Client;
 
@@ -65,11 +64,11 @@ public static partial class OpenIddictClientHandlers
                             description: SR.FormatID2107(parameter.Key),
                             uri: SR.FormatID8000(SR.ID2107));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
 
                 // Note: in the typical case, the response parameters should be deserialized from a
                 // JSON response and thus natively stored as System.Text.Json.JsonElement instances.
@@ -149,10 +148,10 @@ public static partial class OpenIddictClientHandlers
                         description: SR.GetResourceString(SR.ID2146),
                         uri: SR.FormatID8000(SR.ID2146));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -192,7 +191,7 @@ public static partial class OpenIddictClientHandlers
                         description: SR.FormatID2105(Parameters.Active),
                         uri: SR.FormatID8000(SR.ID2105));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 if (active is not true)
@@ -202,10 +201,10 @@ public static partial class OpenIddictClientHandlers
                         description: SR.GetResourceString(SR.ID2106),
                         uri: SR.FormatID8000(SR.ID2106));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -244,7 +243,7 @@ public static partial class OpenIddictClientHandlers
                             description: SR.GetResourceString(SR.ID2108),
                             uri: SR.FormatID8000(SR.ID2108));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
 
                     // Ensure the issuer matches the expected value.
@@ -255,11 +254,11 @@ public static partial class OpenIddictClientHandlers
                             description: SR.GetResourceString(SR.ID2109),
                             uri: SR.FormatID8000(SR.ID2109));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -303,10 +302,10 @@ public static partial class OpenIddictClientHandlers
                         description: SR.GetResourceString(SR.ID2176),
                         uri: SR.FormatID8000(SR.ID2176));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -341,7 +340,7 @@ public static partial class OpenIddictClientHandlers
                 // whether the returned token has an acceptable type depending on the context.
                 switch ((string?) context.Response[Claims.TokenUsage])
                 {
-                    case null or { Length: 0 }: return default;
+                    case null or { Length: 0 }: return ValueTask.CompletedTask;
 
                     // Note: by default, OpenIddict only allows access/refresh tokens to be
                     // introspected but additional types can be added using the events model.
@@ -359,10 +358,10 @@ public static partial class OpenIddictClientHandlers
                             description: SR.GetResourceString(SR.ID2118),
                             uri: SR.FormatID8000(SR.ID2118));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -455,7 +454,7 @@ public static partial class OpenIddictClientHandlers
 
                 context.Principal = new ClaimsPrincipal(identity);
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -521,7 +520,7 @@ public static partial class OpenIddictClientHandlers
                     _ => []
                 });
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Client/OpenIddictClientHandlers.Protection.cs

@@ -11,7 +11,6 @@ using System.Security.Claims;
 using Microsoft.Extensions.Logging;
 using Microsoft.IdentityModel.JsonWebTokens;
 using Microsoft.IdentityModel.Tokens;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Client;
 
@@ -99,7 +98,7 @@ public static partial class OpenIddictClientHandlers
                 context.SecurityTokenHandler = context.Options.JsonWebTokenHandler;
                 context.TokenValidationParameters = parameters;
 
-                return default;
+                return ValueTask.CompletedTask;
 
                 TokenValidationParameters GetClientTokenValidationParameters()
                 {
@@ -215,7 +214,7 @@ public static partial class OpenIddictClientHandlers
                 // If no character was explicitly added, all characters are considered valid.
                 if (context.AllowedCharset.Count is 0)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Remove the disallowed characters from the token string. If the token is
@@ -228,12 +227,12 @@ public static partial class OpenIddictClientHandlers
                         description: SR.GetResourceString(SR.ID2004),
                         uri: SR.FormatID8000(SR.ID2004));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 context.Token = token;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -503,7 +502,7 @@ public static partial class OpenIddictClientHandlers
                 // Note: only map the private claims from fully trusted tokens.
                 if (context.Principal is null || !context.Principal.HasTokenType(TokenTypeIdentifiers.Private.StateToken))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // In OpenIddict 3.0, the creation date of a token is stored in "oi_crt_dt".
@@ -530,7 +529,7 @@ public static partial class OpenIddictClientHandlers
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -638,7 +637,7 @@ public static partial class OpenIddictClientHandlers
                         description: SR.GetResourceString(SR.ID2004),
                         uri: SR.FormatID8000(SR.ID2004));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // When using JWT or Data Protection tokens, the correct token type is always enforced by IdentityModel
@@ -656,7 +655,7 @@ public static partial class OpenIddictClientHandlers
                     throw new InvalidOperationException(SR.FormatID0005(type, string.Join(", ", context.ValidTokenTypes)));
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -694,10 +693,10 @@ public static partial class OpenIddictClientHandlers
                         description: SR.GetResourceString(SR.ID2019),
                         uri: SR.FormatID8000(SR.ID2019));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -730,7 +729,7 @@ public static partial class OpenIddictClientHandlers
                 // If no specific value is expected, skip the default presenter validation.
                 if (context.ValidPresenters.Count is 0)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // If the token doesn't have any presenter attached, return an error.
@@ -744,7 +743,7 @@ public static partial class OpenIddictClientHandlers
                         description: SR.GetResourceString(SR.ID2184),
                         uri: SR.FormatID8000(SR.ID2184));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // If the token doesn't include any registered presenter, return an error.
@@ -757,10 +756,10 @@ public static partial class OpenIddictClientHandlers
                         description: SR.GetResourceString(SR.ID2185),
                         uri: SR.FormatID8000(SR.ID2185));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -793,7 +792,7 @@ public static partial class OpenIddictClientHandlers
                 // If no specific value is expected, skip the default audience validation.
                 if (context.ValidAudiences.Count is 0)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // If the token doesn't have any audience attached, return an error.
@@ -807,7 +806,7 @@ public static partial class OpenIddictClientHandlers
                         description: SR.GetResourceString(SR.ID2093),
                         uri: SR.FormatID8000(SR.ID2093));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // If the token doesn't include any registered audience, return an error.
@@ -820,10 +819,10 @@ public static partial class OpenIddictClientHandlers
                         description: SR.GetResourceString(SR.ID2094),
                         uri: SR.FormatID8000(SR.ID2094));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -949,7 +948,7 @@ public static partial class OpenIddictClientHandlers
                     _ => context.Options.SigningCredentials.First()
                 };
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1056,7 +1055,7 @@ public static partial class OpenIddictClientHandlers
 
                 context.SecurityTokenDescriptor.Subject = (ClaimsIdentity) principal.Identity;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1121,7 +1120,7 @@ public static partial class OpenIddictClientHandlers
                     string value => value
                 };
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1152,7 +1151,7 @@ public static partial class OpenIddictClientHandlers
                 // If a token was already attached by another handler, don't overwrite it.
                 if (!string.IsNullOrEmpty(context.Token))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 context.Token = context.SecurityTokenHandler.CreateToken(context.SecurityTokenDescriptor);
@@ -1160,7 +1159,7 @@ public static partial class OpenIddictClientHandlers
                 context.Logger.LogTrace(6013, SR.GetResourceString(SR.ID6013), context.TokenType,
                     context.Token, context.SecurityTokenDescriptor.Subject?.Claims ?? []);
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 

src/OpenIddict.Client/OpenIddictClientHandlers.Revocation.cs

@@ -55,11 +55,11 @@ public static partial class OpenIddictClientHandlers
                             description: SR.FormatID2107(parameter.Key),
                             uri: SR.FormatID8000(SR.ID2107));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
 
                 // Note: in the typical case, the response parameters should be deserialized from a
                 // JSON response and thus natively stored as System.Text.Json.JsonElement instances.
@@ -116,10 +116,10 @@ public static partial class OpenIddictClientHandlers
                         description: SR.GetResourceString(SR.ID2175),
                         uri: SR.FormatID8000(SR.ID2175));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Client/OpenIddictClientHandlers.Session.cs

@@ -6,7 +6,6 @@
 
 using System.Collections.Immutable;
 using Microsoft.Extensions.Logging;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Client;
 
@@ -170,7 +169,7 @@ public static partial class OpenIddictClientHandlers
                 // Don't overwrite the endpoint URI if it was already set.
                 if (!string.IsNullOrEmpty(context.EndSessionEndpoint))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Ensure the end session endpoint is present and is a valid absolute URI.
@@ -182,7 +181,7 @@ public static partial class OpenIddictClientHandlers
 
                 context.EndSessionEndpoint = context.Configuration.EndSessionEndpoint.AbsoluteUri;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 

src/OpenIddict.Client/OpenIddictClientHandlers.Userinfo.cs

@@ -52,7 +52,7 @@ public static partial class OpenIddictClientHandlers
                 // Ignore the response instance if a userinfo token was extracted.
                 if (!string.IsNullOrEmpty(context.UserInfoToken))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 foreach (var parameter in context.Response.GetParameters())
@@ -64,11 +64,11 @@ public static partial class OpenIddictClientHandlers
                             description: SR.FormatID2107(parameter.Key),
                             uri: SR.FormatID8000(SR.ID2107));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
 
                 // Note: in the typical case, the response parameters should be deserialized from a
                 // JSON response and thus natively stored as System.Text.Json.JsonElement instances.
@@ -131,10 +131,10 @@ public static partial class OpenIddictClientHandlers
                         description: SR.GetResourceString(SR.ID2148),
                         uri: SR.FormatID8000(SR.ID2148));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -166,7 +166,7 @@ public static partial class OpenIddictClientHandlers
                 // Ignore the response instance if a userinfo token was extracted.
                 if (!string.IsNullOrEmpty(context.UserInfoToken))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Create a new claims-based identity using the same authentication type
@@ -225,7 +225,7 @@ public static partial class OpenIddictClientHandlers
 
                 context.Principal = new ClaimsPrincipal(identity);
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Client/OpenIddictClientRetriever.cs

@@ -7,7 +7,6 @@
 using System.ComponentModel;
 using System.Diagnostics.CodeAnalysis;
 using Microsoft.IdentityModel.Protocols;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Client;
 

src/OpenIddict.Client/OpenIddictClientService.cs

@@ -12,7 +12,6 @@ using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Microsoft.IdentityModel.Tokens;
-using OpenIddict.Extensions;
 using static OpenIddict.Abstractions.OpenIddictExceptions;
 using static OpenIddict.Client.OpenIddictClientModels;
 

src/OpenIddict.Core/Managers/OpenIddictApplicationManager.cs

@@ -16,7 +16,6 @@ using System.Text.Json;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Microsoft.IdentityModel.Tokens;
-using OpenIddict.Extensions;
 using ValidationException = OpenIddict.Abstractions.OpenIddictExceptions.ValidationException;
 
 #if !SUPPORTS_KEY_DERIVATION_WITH_SPECIFIED_HASH_ALGORITHM

src/OpenIddict.Core/Managers/OpenIddictAuthorizationManager.cs

@@ -12,7 +12,6 @@ using System.Text;
 using System.Text.Json;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
-using OpenIddict.Extensions;
 using static OpenIddict.Abstractions.OpenIddictExceptions;
 using ValidationException = OpenIddict.Abstractions.OpenIddictExceptions.ValidationException;
 

src/OpenIddict.Core/Managers/OpenIddictTokenManager.cs

@@ -11,7 +11,6 @@ using System.Text;
 using System.Text.Json;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
-using OpenIddict.Extensions;
 using static OpenIddict.Abstractions.OpenIddictExceptions;
 using ValidationException = OpenIddict.Abstractions.OpenIddictExceptions.ValidationException;
 

src/OpenIddict.EntityFramework/OpenIddictEntityFrameworkHelpers.cs

@@ -10,7 +10,6 @@ using System.Runtime.CompilerServices;
 using Microsoft.Extensions.DependencyInjection;
 using OpenIddict.EntityFramework;
 using OpenIddict.EntityFramework.Models;
-using OpenIddict.Extensions;
 
 namespace System.Data.Entity;
 

src/OpenIddict.EntityFramework/Stores/OpenIddictEntityFrameworkApplicationStore.cs

@@ -782,7 +782,7 @@ public class OpenIddictEntityFrameworkApplicationStore<
 
         application.ApplicationType = type;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -795,7 +795,7 @@ public class OpenIddictEntityFrameworkApplicationStore<
 
         application.ClientId = identifier;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -808,7 +808,7 @@ public class OpenIddictEntityFrameworkApplicationStore<
 
         application.ClientSecret = secret;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -821,7 +821,7 @@ public class OpenIddictEntityFrameworkApplicationStore<
 
         application.ClientType = type;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -834,7 +834,7 @@ public class OpenIddictEntityFrameworkApplicationStore<
 
         application.ConsentType = type;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -847,7 +847,7 @@ public class OpenIddictEntityFrameworkApplicationStore<
 
         application.DisplayName = name;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -863,7 +863,7 @@ public class OpenIddictEntityFrameworkApplicationStore<
         {
             application.DisplayNames = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -886,7 +886,7 @@ public class OpenIddictEntityFrameworkApplicationStore<
 
         application.DisplayNames = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -899,7 +899,7 @@ public class OpenIddictEntityFrameworkApplicationStore<
 
         application.JsonWebKeySet = set is not null ? JsonSerializer.Serialize(set, OpenIddictSerializer.Default.JsonWebKeySet) : null;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -914,7 +914,7 @@ public class OpenIddictEntityFrameworkApplicationStore<
         {
             application.Permissions = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -936,7 +936,7 @@ public class OpenIddictEntityFrameworkApplicationStore<
 
         application.Permissions = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -952,7 +952,7 @@ public class OpenIddictEntityFrameworkApplicationStore<
         {
             application.PostLogoutRedirectUris = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -974,7 +974,7 @@ public class OpenIddictEntityFrameworkApplicationStore<
 
         application.PostLogoutRedirectUris = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -990,7 +990,7 @@ public class OpenIddictEntityFrameworkApplicationStore<
         {
             application.Properties = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -1013,7 +1013,7 @@ public class OpenIddictEntityFrameworkApplicationStore<
 
         application.Properties = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1029,7 +1029,7 @@ public class OpenIddictEntityFrameworkApplicationStore<
         {
             application.RedirectUris = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -1051,7 +1051,7 @@ public class OpenIddictEntityFrameworkApplicationStore<
 
         application.RedirectUris = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1066,7 +1066,7 @@ public class OpenIddictEntityFrameworkApplicationStore<
         {
             application.Requirements = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -1088,7 +1088,7 @@ public class OpenIddictEntityFrameworkApplicationStore<
 
         application.Requirements = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1104,7 +1104,7 @@ public class OpenIddictEntityFrameworkApplicationStore<
         {
             application.Settings = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -1127,7 +1127,7 @@ public class OpenIddictEntityFrameworkApplicationStore<
 
         application.Settings = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>

src/OpenIddict.EntityFramework/Stores/OpenIddictEntityFrameworkAuthorizationStore.cs

@@ -16,7 +16,6 @@ using System.Text.Json;
 using Microsoft.Extensions.Caching.Memory;
 using Microsoft.Extensions.Options;
 using OpenIddict.EntityFramework.Models;
-using OpenIddict.Extensions;
 using static OpenIddict.Abstractions.OpenIddictExceptions;
 
 namespace OpenIddict.EntityFramework;
@@ -812,7 +811,7 @@ public class OpenIddictEntityFrameworkAuthorizationStore<
 
         authorization.CreationDate = date?.UtcDateTime;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -828,7 +827,7 @@ public class OpenIddictEntityFrameworkAuthorizationStore<
         {
             authorization.Properties = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -851,7 +850,7 @@ public class OpenIddictEntityFrameworkAuthorizationStore<
 
         authorization.Properties = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -867,7 +866,7 @@ public class OpenIddictEntityFrameworkAuthorizationStore<
         {
             authorization.Scopes = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -889,7 +888,7 @@ public class OpenIddictEntityFrameworkAuthorizationStore<
 
         authorization.Scopes = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -902,7 +901,7 @@ public class OpenIddictEntityFrameworkAuthorizationStore<
 
         authorization.Status = status;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -915,7 +914,7 @@ public class OpenIddictEntityFrameworkAuthorizationStore<
 
         authorization.Subject = subject;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -928,7 +927,7 @@ public class OpenIddictEntityFrameworkAuthorizationStore<
 
         authorization.Type = type;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>

src/OpenIddict.EntityFramework/Stores/OpenIddictEntityFrameworkScopeStore.cs

@@ -531,7 +531,7 @@ public class OpenIddictEntityFrameworkScopeStore<
 
         scope.Description = description;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -547,7 +547,7 @@ public class OpenIddictEntityFrameworkScopeStore<
         {
             scope.Descriptions = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -570,7 +570,7 @@ public class OpenIddictEntityFrameworkScopeStore<
 
         scope.Descriptions = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -583,7 +583,7 @@ public class OpenIddictEntityFrameworkScopeStore<
 
         scope.DisplayName = name;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -599,7 +599,7 @@ public class OpenIddictEntityFrameworkScopeStore<
         {
             scope.DisplayNames = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -622,7 +622,7 @@ public class OpenIddictEntityFrameworkScopeStore<
 
         scope.DisplayNames = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -635,7 +635,7 @@ public class OpenIddictEntityFrameworkScopeStore<
 
         scope.Name = name;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -651,7 +651,7 @@ public class OpenIddictEntityFrameworkScopeStore<
         {
             scope.Properties = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -674,7 +674,7 @@ public class OpenIddictEntityFrameworkScopeStore<
 
         scope.Properties = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -689,7 +689,7 @@ public class OpenIddictEntityFrameworkScopeStore<
         {
             scope.Resources = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -711,7 +711,7 @@ public class OpenIddictEntityFrameworkScopeStore<
 
         scope.Resources = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>

src/OpenIddict.EntityFramework/Stores/OpenIddictEntityFrameworkTokenStore.cs

@@ -16,7 +16,6 @@ using System.Text.Json;
 using Microsoft.Extensions.Caching.Memory;
 using Microsoft.Extensions.Options;
 using OpenIddict.EntityFramework.Models;
-using OpenIddict.Extensions;
 using static OpenIddict.Abstractions.OpenIddictExceptions;
 
 namespace OpenIddict.EntityFramework;
@@ -965,7 +964,7 @@ public class OpenIddictEntityFrameworkTokenStore<
 
         token.CreationDate = date?.UtcDateTime;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -978,7 +977,7 @@ public class OpenIddictEntityFrameworkTokenStore<
 
         token.ExpirationDate = date?.UtcDateTime;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -991,7 +990,7 @@ public class OpenIddictEntityFrameworkTokenStore<
 
         token.Payload = payload;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1007,7 +1006,7 @@ public class OpenIddictEntityFrameworkTokenStore<
         {
             token.Properties = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -1030,7 +1029,7 @@ public class OpenIddictEntityFrameworkTokenStore<
 
         token.Properties = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1043,7 +1042,7 @@ public class OpenIddictEntityFrameworkTokenStore<
 
         token.RedemptionDate = date?.UtcDateTime;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1056,7 +1055,7 @@ public class OpenIddictEntityFrameworkTokenStore<
 
         token.ReferenceId = identifier;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1069,7 +1068,7 @@ public class OpenIddictEntityFrameworkTokenStore<
 
         token.Status = status;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1082,7 +1081,7 @@ public class OpenIddictEntityFrameworkTokenStore<
 
         token.Subject = subject;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1095,7 +1094,7 @@ public class OpenIddictEntityFrameworkTokenStore<
 
         token.Type = type;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>

src/OpenIddict.EntityFrameworkCore/OpenIddictEntityFrameworkCoreHelpers.cs

@@ -10,7 +10,6 @@ using System.Runtime.CompilerServices;
 using Microsoft.Extensions.DependencyInjection;
 using OpenIddict.EntityFrameworkCore;
 using OpenIddict.EntityFrameworkCore.Models;
-using OpenIddict.Extensions;
 
 namespace Microsoft.EntityFrameworkCore;
 

src/OpenIddict.EntityFrameworkCore/Stores/OpenIddictEntityFrameworkCoreApplicationStore.cs

@@ -863,7 +863,7 @@ public class OpenIddictEntityFrameworkCoreApplicationStore<
 
         application.ApplicationType = type;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -876,7 +876,7 @@ public class OpenIddictEntityFrameworkCoreApplicationStore<
 
         application.ClientId = identifier;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -889,7 +889,7 @@ public class OpenIddictEntityFrameworkCoreApplicationStore<
 
         application.ClientSecret = secret;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -902,7 +902,7 @@ public class OpenIddictEntityFrameworkCoreApplicationStore<
 
         application.ClientType = type;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -915,7 +915,7 @@ public class OpenIddictEntityFrameworkCoreApplicationStore<
 
         application.ConsentType = type;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -928,7 +928,7 @@ public class OpenIddictEntityFrameworkCoreApplicationStore<
 
         application.DisplayName = name;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -944,7 +944,7 @@ public class OpenIddictEntityFrameworkCoreApplicationStore<
         {
             application.DisplayNames = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -967,7 +967,7 @@ public class OpenIddictEntityFrameworkCoreApplicationStore<
 
         application.DisplayNames = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -980,7 +980,7 @@ public class OpenIddictEntityFrameworkCoreApplicationStore<
 
         application.JsonWebKeySet = set is not null ? JsonSerializer.Serialize(set, OpenIddictSerializer.Default.JsonWebKeySet) : null;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -995,7 +995,7 @@ public class OpenIddictEntityFrameworkCoreApplicationStore<
         {
             application.Permissions = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -1017,7 +1017,7 @@ public class OpenIddictEntityFrameworkCoreApplicationStore<
 
         application.Permissions = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1033,7 +1033,7 @@ public class OpenIddictEntityFrameworkCoreApplicationStore<
         {
             application.PostLogoutRedirectUris = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -1055,7 +1055,7 @@ public class OpenIddictEntityFrameworkCoreApplicationStore<
 
         application.PostLogoutRedirectUris = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1071,7 +1071,7 @@ public class OpenIddictEntityFrameworkCoreApplicationStore<
         {
             application.Properties = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -1094,7 +1094,7 @@ public class OpenIddictEntityFrameworkCoreApplicationStore<
 
         application.Properties = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1110,7 +1110,7 @@ public class OpenIddictEntityFrameworkCoreApplicationStore<
         {
             application.RedirectUris = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -1132,7 +1132,7 @@ public class OpenIddictEntityFrameworkCoreApplicationStore<
 
         application.RedirectUris = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1147,7 +1147,7 @@ public class OpenIddictEntityFrameworkCoreApplicationStore<
         {
             application.Requirements = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -1169,7 +1169,7 @@ public class OpenIddictEntityFrameworkCoreApplicationStore<
 
         application.Requirements = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1185,7 +1185,7 @@ public class OpenIddictEntityFrameworkCoreApplicationStore<
         {
             application.Settings = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -1208,7 +1208,7 @@ public class OpenIddictEntityFrameworkCoreApplicationStore<
 
         application.Settings = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>

src/OpenIddict.EntityFrameworkCore/Stores/OpenIddictEntityFrameworkCoreAuthorizationStore.cs

@@ -15,7 +15,6 @@ using System.Text.Json;
 using Microsoft.Extensions.Caching.Memory;
 using Microsoft.Extensions.Options;
 using OpenIddict.EntityFrameworkCore.Models;
-using OpenIddict.Extensions;
 using static OpenIddict.Abstractions.OpenIddictExceptions;
 
 namespace OpenIddict.EntityFrameworkCore;
@@ -1016,7 +1015,7 @@ public class OpenIddictEntityFrameworkCoreAuthorizationStore<
 
         authorization.CreationDate = date?.UtcDateTime;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1032,7 +1031,7 @@ public class OpenIddictEntityFrameworkCoreAuthorizationStore<
         {
             authorization.Properties = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -1055,7 +1054,7 @@ public class OpenIddictEntityFrameworkCoreAuthorizationStore<
 
         authorization.Properties = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1071,7 +1070,7 @@ public class OpenIddictEntityFrameworkCoreAuthorizationStore<
         {
             authorization.Scopes = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -1093,7 +1092,7 @@ public class OpenIddictEntityFrameworkCoreAuthorizationStore<
 
         authorization.Scopes = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1107,7 +1106,7 @@ public class OpenIddictEntityFrameworkCoreAuthorizationStore<
 
         authorization.Status = status;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1121,7 +1120,7 @@ public class OpenIddictEntityFrameworkCoreAuthorizationStore<
 
         authorization.Subject = subject;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1135,7 +1134,7 @@ public class OpenIddictEntityFrameworkCoreAuthorizationStore<
 
         authorization.Type = type;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>

src/OpenIddict.EntityFrameworkCore/Stores/OpenIddictEntityFrameworkCoreScopeStore.cs

@@ -545,7 +545,7 @@ public class OpenIddictEntityFrameworkCoreScopeStore<
 
         scope.Description = description;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -561,7 +561,7 @@ public class OpenIddictEntityFrameworkCoreScopeStore<
         {
             scope.Descriptions = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -584,7 +584,7 @@ public class OpenIddictEntityFrameworkCoreScopeStore<
 
         scope.Descriptions = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -597,7 +597,7 @@ public class OpenIddictEntityFrameworkCoreScopeStore<
 
         scope.DisplayName = name;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -613,7 +613,7 @@ public class OpenIddictEntityFrameworkCoreScopeStore<
         {
             scope.DisplayNames = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -636,7 +636,7 @@ public class OpenIddictEntityFrameworkCoreScopeStore<
 
         scope.DisplayNames = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -649,7 +649,7 @@ public class OpenIddictEntityFrameworkCoreScopeStore<
 
         scope.Name = name;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -665,7 +665,7 @@ public class OpenIddictEntityFrameworkCoreScopeStore<
         {
             scope.Properties = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -688,7 +688,7 @@ public class OpenIddictEntityFrameworkCoreScopeStore<
 
         scope.Properties = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -703,7 +703,7 @@ public class OpenIddictEntityFrameworkCoreScopeStore<
         {
             scope.Resources = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -725,7 +725,7 @@ public class OpenIddictEntityFrameworkCoreScopeStore<
 
         scope.Resources = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>

src/OpenIddict.EntityFrameworkCore/Stores/OpenIddictEntityFrameworkCoreTokenStore.cs

@@ -15,7 +15,6 @@ using System.Text.Json;
 using Microsoft.Extensions.Caching.Memory;
 using Microsoft.Extensions.Options;
 using OpenIddict.EntityFrameworkCore.Models;
-using OpenIddict.Extensions;
 using static OpenIddict.Abstractions.OpenIddictExceptions;
 
 namespace OpenIddict.EntityFrameworkCore;
@@ -1170,7 +1169,7 @@ public class OpenIddictEntityFrameworkCoreTokenStore<
 
         token.CreationDate = date?.UtcDateTime;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1183,7 +1182,7 @@ public class OpenIddictEntityFrameworkCoreTokenStore<
 
         token.ExpirationDate = date?.UtcDateTime;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1196,7 +1195,7 @@ public class OpenIddictEntityFrameworkCoreTokenStore<
 
         token.Payload = payload;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1212,7 +1211,7 @@ public class OpenIddictEntityFrameworkCoreTokenStore<
         {
             token.Properties = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -1235,7 +1234,7 @@ public class OpenIddictEntityFrameworkCoreTokenStore<
 
         token.Properties = Encoding.UTF8.GetString(stream.ToArray());
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1248,7 +1247,7 @@ public class OpenIddictEntityFrameworkCoreTokenStore<
 
         token.RedemptionDate = date?.UtcDateTime;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1261,7 +1260,7 @@ public class OpenIddictEntityFrameworkCoreTokenStore<
 
         token.ReferenceId = identifier;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1274,7 +1273,7 @@ public class OpenIddictEntityFrameworkCoreTokenStore<
 
         token.Status = status;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1287,7 +1286,7 @@ public class OpenIddictEntityFrameworkCoreTokenStore<
 
         token.Subject = subject;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -1300,7 +1299,7 @@ public class OpenIddictEntityFrameworkCoreTokenStore<
 
         token.Type = type;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>

src/OpenIddict.MongoDb/Stores/OpenIddictMongoDbApplicationStore.cs

@@ -508,7 +508,7 @@ public class OpenIddictMongoDbApplicationStore<
 
         application.ApplicationType = type;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -522,7 +522,7 @@ public class OpenIddictMongoDbApplicationStore<
 
         application.ClientId = identifier;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -536,7 +536,7 @@ public class OpenIddictMongoDbApplicationStore<
 
         application.ClientSecret = secret;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -550,7 +550,7 @@ public class OpenIddictMongoDbApplicationStore<
 
         application.ClientType = type;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -564,7 +564,7 @@ public class OpenIddictMongoDbApplicationStore<
 
         application.ConsentType = type;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -578,7 +578,7 @@ public class OpenIddictMongoDbApplicationStore<
 
         application.DisplayName = name;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -594,14 +594,14 @@ public class OpenIddictMongoDbApplicationStore<
         {
             application.DisplayNames = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         application.DisplayNames = names.ToImmutableDictionary(
             pair => pair.Key.Name,
             pair => pair.Value);
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -616,7 +616,7 @@ public class OpenIddictMongoDbApplicationStore<
         application.JsonWebKeySet = set is not null ? BsonDocument.Parse(
             JsonSerializer.Serialize(set, OpenIddictSerializer.Default.JsonWebKeySet)) : null;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -632,12 +632,12 @@ public class OpenIddictMongoDbApplicationStore<
         {
             application.Permissions = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         application.Permissions = permissions.ToImmutableList();
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -653,12 +653,12 @@ public class OpenIddictMongoDbApplicationStore<
         {
             application.PostLogoutRedirectUris = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         application.PostLogoutRedirectUris = uris.ToImmutableList();
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -674,7 +674,7 @@ public class OpenIddictMongoDbApplicationStore<
         {
             application.Properties = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -697,7 +697,7 @@ public class OpenIddictMongoDbApplicationStore<
 
         application.Properties = BsonDocument.Parse(Encoding.UTF8.GetString(stream.ToArray()));
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -713,12 +713,12 @@ public class OpenIddictMongoDbApplicationStore<
         {
             application.RedirectUris = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         application.RedirectUris = uris.ToImmutableList();
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -734,12 +734,12 @@ public class OpenIddictMongoDbApplicationStore<
         {
             application.Requirements = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         application.Requirements = requirements.ToImmutableList();
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -755,12 +755,12 @@ public class OpenIddictMongoDbApplicationStore<
         {
             application.Settings = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         application.Settings = settings;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>

src/OpenIddict.MongoDb/Stores/OpenIddictMongoDbAuthorizationStore.cs

@@ -11,7 +11,6 @@ using System.Text;
 using System.Text.Encodings.Web;
 using System.Text.Json;
 using Microsoft.Extensions.Options;
-using OpenIddict.Extensions;
 using OpenIddict.MongoDb.Models;
 using static OpenIddict.Abstractions.OpenIddictExceptions;
 
@@ -443,9 +442,11 @@ public class OpenIddictMongoDbAuthorizationStore<
 
         // Note: to avoid generating delete requests with very large filters, a buffer is used here and the
         // maximum number of elements that can be removed by a single call to PruneAsync() is deliberately limited.
-        foreach (var buffer in identifiers.Take(1_000_000).Buffer(1_000))
+        foreach (var buffer in identifiers.Take(1_000_000).Chunk(1_000))
         {
-            result += (await collection.DeleteManyAsync(authorization => buffer.Contains(authorization.Id), cancellationToken)).DeletedCount;
+            // Note: Enumerable.Contains() is deliberately used without the extension method syntax to ensure the
+            // span-based MemoryExtensions.Contains() API (which is not supported by MongoDB) is not used instead.
+            result += (await collection.DeleteManyAsync(authorization => Enumerable.Contains(buffer, authorization.Id), cancellationToken)).DeletedCount;
         }
 
         return result;
@@ -541,7 +542,7 @@ public class OpenIddictMongoDbAuthorizationStore<
             authorization.ApplicationId = ObjectId.Empty;
         }
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -555,7 +556,7 @@ public class OpenIddictMongoDbAuthorizationStore<
 
         authorization.CreationDate = date?.UtcDateTime;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -571,7 +572,7 @@ public class OpenIddictMongoDbAuthorizationStore<
         {
             authorization.Properties = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -594,7 +595,7 @@ public class OpenIddictMongoDbAuthorizationStore<
 
         authorization.Properties = BsonDocument.Parse(Encoding.UTF8.GetString(stream.ToArray()));
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -610,12 +611,12 @@ public class OpenIddictMongoDbAuthorizationStore<
         {
             authorization.Scopes = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         authorization.Scopes = scopes.ToImmutableList();
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -628,7 +629,7 @@ public class OpenIddictMongoDbAuthorizationStore<
 
         authorization.Status = status;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -641,7 +642,7 @@ public class OpenIddictMongoDbAuthorizationStore<
 
         authorization.Subject = subject;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -654,7 +655,7 @@ public class OpenIddictMongoDbAuthorizationStore<
 
         authorization.Type = type;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>

src/OpenIddict.MongoDb/Stores/OpenIddictMongoDbScopeStore.cs

@@ -397,7 +397,7 @@ public class OpenIddictMongoDbScopeStore<
 
         scope.Description = description;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -413,14 +413,14 @@ public class OpenIddictMongoDbScopeStore<
         {
             scope.Descriptions = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         scope.Descriptions = descriptions.ToImmutableDictionary(
             pair => pair.Key.Name,
             pair => pair.Value);
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -436,14 +436,14 @@ public class OpenIddictMongoDbScopeStore<
         {
             scope.DisplayNames = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         scope.DisplayNames = names.ToImmutableDictionary(
             pair => pair.Key.Name,
             pair => pair.Value);
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -456,7 +456,7 @@ public class OpenIddictMongoDbScopeStore<
 
         scope.DisplayName = name;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -469,7 +469,7 @@ public class OpenIddictMongoDbScopeStore<
 
         scope.Name = name;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -485,7 +485,7 @@ public class OpenIddictMongoDbScopeStore<
         {
             scope.Properties = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -508,7 +508,7 @@ public class OpenIddictMongoDbScopeStore<
 
         scope.Properties = BsonDocument.Parse(Encoding.UTF8.GetString(stream.ToArray()));
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -523,12 +523,12 @@ public class OpenIddictMongoDbScopeStore<
         {
             scope.Resources = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         scope.Resources = resources.ToImmutableList();
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>

src/OpenIddict.MongoDb/Stores/OpenIddictMongoDbTokenStore.cs

@@ -11,7 +11,6 @@ using System.Text;
 using System.Text.Encodings.Web;
 using System.Text.Json;
 using Microsoft.Extensions.Options;
-using OpenIddict.Extensions;
 using OpenIddict.MongoDb.Models;
 using static OpenIddict.Abstractions.OpenIddictExceptions;
 
@@ -519,9 +518,11 @@ public class OpenIddictMongoDbTokenStore<
 
         // Note: to avoid generating delete requests with very large filters, a buffer is used here and the
         // maximum number of elements that can be removed by a single call to PruneAsync() is deliberately limited.
-        foreach (var buffer in identifiers.Take(1_000_000).Buffer(1_000))
+        foreach (var buffer in identifiers.Take(1_000_000).Chunk(1_000))
         {
-            result += (await collection.DeleteManyAsync(token => buffer.Contains(token.Id), cancellationToken)).DeletedCount;
+            // Note: Enumerable.Contains() is deliberately used without the extension method syntax to ensure the
+            // span-based MemoryExtensions.Contains() API (which is not supported by MongoDB) is not used instead.
+            result += (await collection.DeleteManyAsync(token => Enumerable.Contains(buffer, token.Id), cancellationToken)).DeletedCount;
         }
 
         return result;
@@ -634,7 +635,7 @@ public class OpenIddictMongoDbTokenStore<
             token.ApplicationId = ObjectId.Empty;
         }
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -655,7 +656,7 @@ public class OpenIddictMongoDbTokenStore<
             token.AuthorizationId = ObjectId.Empty;
         }
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -668,7 +669,7 @@ public class OpenIddictMongoDbTokenStore<
 
         token.CreationDate = date?.UtcDateTime;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -681,7 +682,7 @@ public class OpenIddictMongoDbTokenStore<
 
         token.ExpirationDate = date?.UtcDateTime;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -694,7 +695,7 @@ public class OpenIddictMongoDbTokenStore<
 
         token.Payload = payload;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -710,7 +711,7 @@ public class OpenIddictMongoDbTokenStore<
         {
             token.Properties = null;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
 
         using var stream = new MemoryStream();
@@ -733,7 +734,7 @@ public class OpenIddictMongoDbTokenStore<
 
         token.Properties = BsonDocument.Parse(Encoding.UTF8.GetString(stream.ToArray()));
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -746,7 +747,7 @@ public class OpenIddictMongoDbTokenStore<
 
         token.RedemptionDate = date?.UtcDateTime;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -759,7 +760,7 @@ public class OpenIddictMongoDbTokenStore<
 
         token.ReferenceId = identifier;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -772,7 +773,7 @@ public class OpenIddictMongoDbTokenStore<
 
         token.Status = status;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -785,7 +786,7 @@ public class OpenIddictMongoDbTokenStore<
 
         token.Subject = subject;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>
@@ -798,7 +799,7 @@ public class OpenIddictMongoDbTokenStore<
 
         token.Type = type;
 
-        return default;
+        return ValueTask.CompletedTask;
     }
 
     /// <inheritdoc/>

src/OpenIddict.Quartz/OpenIddictQuartzJob.cs

@@ -7,7 +7,6 @@
 using System.ComponentModel;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Options;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Quartz;
 

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

@@ -91,7 +91,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
 
                 if (string.IsNullOrEmpty(context.Response.RequestUri))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
@@ -124,7 +124,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                 response.Redirect(location);
                 context.HandleRequest();
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -252,7 +252,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                 if (string.IsNullOrEmpty(context.RedirectUri) ||
                    !string.Equals(context.ResponseMode, ResponseModes.Query, StringComparison.Ordinal))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 context.Logger.LogInformation(6148, SR.GetResourceString(SR.ID6148), context.RedirectUri, context.Response);
@@ -286,7 +286,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                 response.Redirect(location);
                 context.HandleRequest();
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -323,7 +323,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                 if (string.IsNullOrEmpty(context.RedirectUri) ||
                    !string.Equals(context.ResponseMode, ResponseModes.Fragment, StringComparison.Ordinal))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 context.Logger.LogInformation(6149, SR.GetResourceString(SR.ID6149), context.RedirectUri, context.Response);
@@ -350,7 +350,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                 response.Redirect(builder.ToString());
                 context.HandleRequest();
 
-                return default;
+                return ValueTask.CompletedTask;
 
                 static bool Contains(StringBuilder builder, char delimiter)
                 {

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

@@ -89,7 +89,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
             if (!string.IsNullOrEmpty(context.Response.Error) &&
                 !string.Equals(context.Response.Error, Errors.AccessDenied, StringComparison.Ordinal))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             var properties = context.Transaction.GetProperty<AuthenticationProperties>(typeof(AuthenticationProperties).FullName!);
@@ -101,7 +101,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                 context.HandleRequest();
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 }

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

@@ -73,7 +73,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
 
                 if (string.IsNullOrEmpty(context.Response.RequestUri))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
@@ -106,7 +106,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                 response.Redirect(location);
                 context.HandleRequest();
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -142,7 +142,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
 
                 if (string.IsNullOrEmpty(context.PostLogoutRedirectUri))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 context.Logger.LogInformation(6151, SR.GetResourceString(SR.ID6151), context.PostLogoutRedirectUri, context.Response);
@@ -176,7 +176,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                 response.Redirect(location);
                 context.HandleRequest();
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -215,7 +215,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                 if (!string.IsNullOrEmpty(context.PostLogoutRedirectUri) ||
                     !string.IsNullOrEmpty(context.Response.Error))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 var properties = context.Transaction.GetProperty<AuthenticationProperties>(typeof(AuthenticationProperties).FullName!);
@@ -227,7 +227,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                     context.HandleRequest();
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Server.AspNetCore/OpenIddictServerAspNetCoreHandlers.cs

@@ -18,7 +18,6 @@ using Microsoft.AspNetCore.Http.Extensions;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Microsoft.Net.Http.Headers;
-using OpenIddict.Extensions;
 using Properties = OpenIddict.Server.AspNetCore.OpenIddictServerAspNetCoreConstants.Properties;
 
 namespace OpenIddict.Server.AspNetCore;
@@ -105,7 +104,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
             context.BaseUri = CreateUri(UriHelper.BuildAbsolute(request.Scheme, host, request.PathBase));
             context.RequestUri = CreateUri(UriHelper.BuildAbsolute(request.Scheme, host, request.PathBase, request.Path, request.QueryString));
 
-            return default;
+            return ValueTask.CompletedTask;
 
             // Note: the BCL System.Uri class has strict rules (e.g it rejects specific characters and enforces a
             // limit of 65519 characters for the complete URI representation). To ensure no exception is thrown if the
@@ -153,10 +152,10 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                     description: SR.GetResourceString(SR.ID2083),
                     uri: SR.FormatID8000(SR.ID2083));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -198,10 +197,10 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                     description: SR.FormatID2081(HeaderNames.Host),
                     uri: SR.FormatID8000(SR.ID2081));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -264,7 +263,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                 }
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -302,7 +301,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                 context.Response.Scope = properties.GetString(Properties.Scope);
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -365,7 +364,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                 }
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -428,7 +427,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                 }
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -476,10 +475,10 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                     description: SR.GetResourceString(SR.ID2084),
                     uri: SR.FormatID8000(SR.ID2084));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -682,7 +681,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                     description: SR.FormatID2174(ClientAuthenticationMethods.ClientSecretPost),
                     uri: SR.FormatID8000(SR.ID2174));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Reject requests that use client_secret_basic if support was explicitly disabled in the options.
@@ -700,10 +699,10 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                     description: SR.FormatID2174(ClientAuthenticationMethods.ClientSecretBasic),
                     uri: SR.FormatID8000(SR.ID2174));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -743,7 +742,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
             string? header = request.Headers[HeaderNames.Authorization];
             if (string.IsNullOrEmpty(header) || !header.StartsWith("Basic ", StringComparison.OrdinalIgnoreCase))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // At this point, reject requests that use multiple client authentication methods.
@@ -758,7 +757,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                     description: SR.GetResourceString(SR.ID2087),
                     uri: SR.FormatID8000(SR.ID2087));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             try
@@ -774,14 +773,14 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                         description: SR.GetResourceString(SR.ID2055),
                         uri: SR.FormatID8000(SR.ID2055));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Attach the basic authentication credentials to the request message.
                 context.Transaction.Request.ClientId = UnescapeDataString(data[..index]);
                 context.Transaction.Request.ClientSecret = UnescapeDataString(data[(index + 1)..]);
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             catch (Exception exception) when (!OpenIddictHelpers.IsFatal(exception))
@@ -791,7 +790,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                     description: SR.GetResourceString(SR.ID2055),
                     uri: SR.FormatID8000(SR.ID2055));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             static string? UnescapeDataString(string data)
@@ -842,13 +841,13 @@ public static partial class OpenIddictServerAspNetCoreHandlers
             string? header = request.Headers[HeaderNames.Authorization];
             if (string.IsNullOrEmpty(header) || !header.StartsWith("Bearer ", StringComparison.OrdinalIgnoreCase))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Attach the access token to the request message.
             context.Transaction.Request.AccessToken = header["Bearer ".Length..];
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -888,7 +887,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                 case OpenIddictServerEndpointType.Authorization when
                     context.Options.EnableAuthorizationRequestCaching &&
                     string.IsNullOrEmpty(context.Transaction.Request?.RequestUri):
-                    return default;
+                    return ValueTask.CompletedTask;
 
                 // When end session request caching is enabled and the request doesn't contain a
                 // request_uri yet, do not enable the pass-through mode to allow OpenIddict to trigger
@@ -896,12 +895,12 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                 case OpenIddictServerEndpointType.EndSession when
                     context.Options.EnableEndSessionRequestCaching &&
                     string.IsNullOrEmpty(context.Transaction.Request?.RequestUri):
-                    return default;
+                    return ValueTask.CompletedTask;
 
             }
 
             context.SkipRequest();
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -967,7 +966,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
                 _ => 400
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1006,7 +1005,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
             response.Headers[HeaderNames.Pragma] = "no-cache";
             response.Headers[HeaderNames.Expires] = "Thu, 01 Jan 1970 00:00:00 GMT";
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1049,7 +1048,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
 
             if (string.IsNullOrEmpty(context.Transaction.Response.Error))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             var scheme = (context.EndpointType, context.Transaction.Response.Error) switch
@@ -1074,7 +1073,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
 
             if (string.IsNullOrEmpty(scheme))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             var parameters = new Dictionary<string, string>(StringComparer.Ordinal);
@@ -1128,7 +1127,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
 
             response.Headers.Append(HeaderNames.WWWAuthenticate, builder.ToString());
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1165,13 +1164,13 @@ public static partial class OpenIddictServerAspNetCoreHandlers
             // If the response doesn't contain a WWW-Authenticate header, don't return an empty response.
             if (!response.Headers.ContainsKey(HeaderNames.WWWAuthenticate))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             context.Logger.LogInformation(6141, SR.GetResourceString(SR.ID6141), context.Transaction.Response);
             context.HandleRequest();
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1268,12 +1267,12 @@ public static partial class OpenIddictServerAspNetCoreHandlers
 
             if (string.IsNullOrEmpty(context.Transaction.Response.Error))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             context.SkipRequest();
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1313,7 +1312,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
 
             if (string.IsNullOrEmpty(context.Transaction.Response.Error))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Determine if the status code pages middleware has been enabled for this request.
@@ -1322,7 +1321,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
             var feature = response.HttpContext.Features.Get<IStatusCodePagesFeature>();
             if (feature is not { Enabled: true })
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Mark the request as fully handled to prevent the other OpenIddict server handlers
@@ -1330,7 +1329,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
             // to rewrite the response using the logic defined by the developer when registering it.
             context.HandleRequest();
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1437,7 +1436,7 @@ public static partial class OpenIddictServerAspNetCoreHandlers
             context.Logger.LogInformation(6145, SR.GetResourceString(SR.ID6145));
             context.HandleRequest();
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 }

src/OpenIddict.Server.DataProtection/OpenIddictServerDataProtectionHandlers.Protection.cs

@@ -10,7 +10,6 @@ using Microsoft.AspNetCore.DataProtection;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Microsoft.IdentityModel.Tokens;
-using OpenIddict.Extensions;
 using static OpenIddict.Server.DataProtection.OpenIddictServerDataProtectionConstants.Purposes;
 using static OpenIddict.Server.OpenIddictServerHandlers.Protection;
 using Schemes = OpenIddict.Server.DataProtection.OpenIddictServerDataProtectionConstants.Purposes.Schemes;
@@ -61,13 +60,13 @@ public static partial class OpenIddictServerDataProtectionHandlers
                 // If a principal was already attached, don't overwrite it.
                 if (context.Principal is not null)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // If a specific token format is expected, return immediately if it doesn't match the expected value.
                 if (context.TokenFormat is not null and not TokenFormats.Private.DataProtection)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Note: ASP.NET Core Data Protection tokens created by the default implementation always start
@@ -84,7 +83,7 @@ public static partial class OpenIddictServerDataProtectionHandlers
                         "Microsoft.AspNetCore.DataProtection.KeyManagement.KeyRingBasedDataProtectionProvider",
                         StringComparison.Ordinal))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Tokens generated using ASP.NET Core Data Protection are encrypted by symmetric keys
@@ -178,14 +177,14 @@ public static partial class OpenIddictServerDataProtectionHandlers
                         description: SR.GetResourceString(SR.ID2004),
                         uri: SR.FormatID8000(SR.ID2004));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 context.Principal = principal;
 
                 context.Logger.LogTrace(6152, SR.GetResourceString(SR.ID6152), context.Token, context.Principal.Claims);
 
-                return default;
+                return ValueTask.CompletedTask;
 
                 ClaimsPrincipal? ValidateToken(string type)
                 {
@@ -306,7 +305,7 @@ public static partial class OpenIddictServerDataProtectionHandlers
                     _ => context.TokenFormat // Don't override the format if the token type is not supported.
                 };
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -342,7 +341,7 @@ public static partial class OpenIddictServerDataProtectionHandlers
                 // If an access token was already attached by another handler, don't overwrite it.
                 if (!string.IsNullOrEmpty(context.Token))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Create a Data Protection protector using the provider registered in the options.
@@ -394,7 +393,7 @@ public static partial class OpenIddictServerDataProtectionHandlers
                 context.Logger.LogTrace(6016, SR.GetResourceString(SR.ID6016), context.TokenType,
                     context.Token, context.Principal.Claims);
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

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

@@ -93,7 +93,7 @@ public static partial class OpenIddictServerOwinHandlers
 
                 if (string.IsNullOrEmpty(context.Response.RequestUri))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
@@ -116,7 +116,7 @@ public static partial class OpenIddictServerOwinHandlers
                 response.Redirect(location);
                 context.HandleRequest();
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -244,7 +244,7 @@ public static partial class OpenIddictServerOwinHandlers
                 if (string.IsNullOrEmpty(context.RedirectUri) ||
                    !string.Equals(context.ResponseMode, ResponseModes.Query, StringComparison.Ordinal))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 context.Logger.LogInformation(6148, SR.GetResourceString(SR.ID6148), context.RedirectUri, context.Response);
@@ -268,7 +268,7 @@ public static partial class OpenIddictServerOwinHandlers
                 response.Redirect(location);
                 context.HandleRequest();
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -305,7 +305,7 @@ public static partial class OpenIddictServerOwinHandlers
                 if (string.IsNullOrEmpty(context.RedirectUri) ||
                    !string.Equals(context.ResponseMode, ResponseModes.Fragment, StringComparison.Ordinal))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 context.Logger.LogInformation(6149, SR.GetResourceString(SR.ID6149), context.RedirectUri, context.Response);
@@ -332,7 +332,7 @@ public static partial class OpenIddictServerOwinHandlers
                 response.Redirect(builder.ToString());
                 context.HandleRequest();
 
-                return default;
+                return ValueTask.CompletedTask;
 
                 static bool Contains(StringBuilder builder, char delimiter)
                 {

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

@@ -92,7 +92,7 @@ public static partial class OpenIddictServerOwinHandlers
             if (!string.IsNullOrEmpty(context.Response.Error) &&
                 !string.Equals(context.Response.Error, Errors.AccessDenied, StringComparison.Ordinal))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             var properties = context.Transaction.GetProperty<AuthenticationProperties>(typeof(AuthenticationProperties).FullName!);
@@ -104,7 +104,7 @@ public static partial class OpenIddictServerOwinHandlers
                 context.HandleRequest();
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 }

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

@@ -73,7 +73,7 @@ public static partial class OpenIddictServerOwinHandlers
 
                 if (string.IsNullOrEmpty(context.Response.RequestUri))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
@@ -95,7 +95,7 @@ public static partial class OpenIddictServerOwinHandlers
 
                 response.Redirect(location);
                 context.HandleRequest();
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -131,7 +131,7 @@ public static partial class OpenIddictServerOwinHandlers
 
                 if (string.IsNullOrEmpty(context.PostLogoutRedirectUri))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 context.Logger.LogInformation(6151, SR.GetResourceString(SR.ID6151), context.PostLogoutRedirectUri, context.Response);
@@ -155,7 +155,7 @@ public static partial class OpenIddictServerOwinHandlers
                 response.Redirect(location);
                 context.HandleRequest();
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -194,7 +194,7 @@ public static partial class OpenIddictServerOwinHandlers
                 if (!string.IsNullOrEmpty(context.PostLogoutRedirectUri) ||
                     !string.IsNullOrEmpty(context.Response.Error))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 var properties = context.Transaction.GetProperty<AuthenticationProperties>(typeof(AuthenticationProperties).FullName!);
@@ -206,7 +206,7 @@ public static partial class OpenIddictServerOwinHandlers
                     context.HandleRequest();
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Server.Owin/OpenIddictServerOwinHandlers.cs

@@ -14,7 +14,6 @@ using System.Text.Json;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Microsoft.Extensions.Primitives;
-using OpenIddict.Extensions;
 using Owin;
 using static OpenIddict.Server.Owin.OpenIddictServerOwinConstants;
 using Properties = OpenIddict.Server.Owin.OpenIddictServerOwinConstants.Properties;
@@ -103,7 +102,7 @@ public static partial class OpenIddictServerOwinHandlers
             context.BaseUri = CreateUri(request.Scheme + Uri.SchemeDelimiter + host + request.PathBase);
             context.RequestUri = CreateUri(request.Scheme + Uri.SchemeDelimiter + host + request.PathBase + request.Path + request.QueryString);
 
-            return default;
+            return ValueTask.CompletedTask;
 
             // Note: the BCL System.Uri class has strict rules (e.g it rejects specific characters and enforces a
             // limit of 65519 characters for the complete URI representation). To ensure no exception is thrown if the
@@ -151,10 +150,10 @@ public static partial class OpenIddictServerOwinHandlers
                     description: SR.GetResourceString(SR.ID2083),
                     uri: SR.FormatID8000(SR.ID2083));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -197,10 +196,10 @@ public static partial class OpenIddictServerOwinHandlers
                     description: SR.FormatID2081(Headers.Host),
                     uri: SR.FormatID8000(SR.ID2081));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -233,7 +232,7 @@ public static partial class OpenIddictServerOwinHandlers
             var properties = context.Transaction.GetProperty<AuthenticationProperties>(typeof(AuthenticationProperties).FullName!);
             if (properties is not { Dictionary.Count: > 0 })
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Note: unlike ASP.NET Core, OWIN's AuthenticationProperties doesn't offer a strongly-typed
@@ -279,7 +278,7 @@ public static partial class OpenIddictServerOwinHandlers
                 }
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -317,7 +316,7 @@ public static partial class OpenIddictServerOwinHandlers
                 context.Response.Scope = GetProperty(properties, Properties.Scope);
             }
 
-            return default;
+            return ValueTask.CompletedTask;
 
             static string? GetProperty(AuthenticationProperties properties, string name)
                 => properties.Dictionary.TryGetValue(name, out string? value) ? value : null;
@@ -353,7 +352,7 @@ public static partial class OpenIddictServerOwinHandlers
             var properties = context.Transaction.GetProperty<AuthenticationProperties>(typeof(AuthenticationProperties).FullName!);
             if (properties is not { Dictionary.Count: > 0 })
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Note: unlike ASP.NET Core, OWIN's AuthenticationProperties doesn't offer a strongly-typed
@@ -399,7 +398,7 @@ public static partial class OpenIddictServerOwinHandlers
                 }
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -432,7 +431,7 @@ public static partial class OpenIddictServerOwinHandlers
             var properties = context.Transaction.GetProperty<AuthenticationProperties>(typeof(AuthenticationProperties).FullName!);
             if (properties is not { Dictionary.Count: > 0 })
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Note: unlike ASP.NET Core, OWIN's AuthenticationProperties doesn't offer a strongly-typed
@@ -478,7 +477,7 @@ public static partial class OpenIddictServerOwinHandlers
                 }
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -529,10 +528,10 @@ public static partial class OpenIddictServerOwinHandlers
                     description: SR.GetResourceString(SR.ID2084),
                     uri: SR.FormatID8000(SR.ID2084));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -744,7 +743,7 @@ public static partial class OpenIddictServerOwinHandlers
                     description: SR.FormatID2174(ClientAuthenticationMethods.ClientSecretPost),
                     uri: SR.FormatID8000(SR.ID2174));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Reject requests that use client_secret_basic if support was explicitly disabled in the options.
@@ -759,10 +758,10 @@ public static partial class OpenIddictServerOwinHandlers
                     description: SR.FormatID2174(ClientAuthenticationMethods.ClientSecretBasic),
                     uri: SR.FormatID8000(SR.ID2174));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -802,7 +801,7 @@ public static partial class OpenIddictServerOwinHandlers
             var header = request.Headers[Headers.Authorization];
             if (string.IsNullOrEmpty(header) || !header.StartsWith("Basic ", StringComparison.OrdinalIgnoreCase))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // At this point, reject requests that use multiple client authentication methods.
@@ -817,7 +816,7 @@ public static partial class OpenIddictServerOwinHandlers
                     description: SR.GetResourceString(SR.ID2087),
                     uri: SR.FormatID8000(SR.ID2087));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             try
@@ -833,14 +832,14 @@ public static partial class OpenIddictServerOwinHandlers
                         description: SR.GetResourceString(SR.ID2055),
                         uri: SR.FormatID8000(SR.ID2055));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Attach the basic authentication credentials to the request message.
                 context.Transaction.Request.ClientId = UnescapeDataString(data[..index]);
                 context.Transaction.Request.ClientSecret = UnescapeDataString(data[(index + 1)..]);
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             catch (Exception exception) when (!OpenIddictHelpers.IsFatal(exception))
@@ -850,7 +849,7 @@ public static partial class OpenIddictServerOwinHandlers
                     description: SR.GetResourceString(SR.ID2055),
                     uri: SR.FormatID8000(SR.ID2055));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             static string? UnescapeDataString(string data)
@@ -901,13 +900,13 @@ public static partial class OpenIddictServerOwinHandlers
             var header = request.Headers[Headers.Authorization];
             if (string.IsNullOrEmpty(header) || !header.StartsWith("Bearer ", StringComparison.OrdinalIgnoreCase))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Attach the access token to the request message.
             context.Transaction.Request.AccessToken = header["Bearer ".Length..];
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -947,7 +946,7 @@ public static partial class OpenIddictServerOwinHandlers
                 case OpenIddictServerEndpointType.Authorization when
                     context.Options.EnableAuthorizationRequestCaching &&
                     string.IsNullOrEmpty(context.Transaction.Request?.RequestUri):
-                    return default;
+                    return ValueTask.CompletedTask;
 
                 // When end session request caching is enabled and the request doesn't contain a
                 // request_uri yet, do not enable the pass-through mode to allow OpenIddict to trigger
@@ -955,12 +954,12 @@ public static partial class OpenIddictServerOwinHandlers
                 case OpenIddictServerEndpointType.EndSession when
                     context.Options.EnableEndSessionRequestCaching &&
                     string.IsNullOrEmpty(context.Transaction.Request?.RequestUri):
-                    return default;
+                    return ValueTask.CompletedTask;
 
             }
 
             context.SkipRequest();
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1026,7 +1025,7 @@ public static partial class OpenIddictServerOwinHandlers
                 _ => 400
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1079,7 +1078,7 @@ public static partial class OpenIddictServerOwinHandlers
                     properties         : response.Context.Authentication.AuthenticationResponseChallenge?.Properties ?? new());
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1124,7 +1123,7 @@ public static partial class OpenIddictServerOwinHandlers
                 TrySuppressFormsAuthenticationRedirect(response.Environment);
             }
 
-            return default;
+            return ValueTask.CompletedTask;
 
             static void TrySuppressFormsAuthenticationRedirect(IDictionary<string, object> environment)
             {
@@ -1185,7 +1184,7 @@ public static partial class OpenIddictServerOwinHandlers
             response.Headers[Headers.Pragma] = "no-cache";
             response.Headers[Headers.Expires] = "Thu, 01 Jan 1970 00:00:00 GMT";
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1228,7 +1227,7 @@ public static partial class OpenIddictServerOwinHandlers
 
             if (string.IsNullOrEmpty(context.Transaction.Response.Error))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             var scheme = (context.EndpointType, context.Transaction.Response.Error) switch
@@ -1253,7 +1252,7 @@ public static partial class OpenIddictServerOwinHandlers
 
             if (string.IsNullOrEmpty(scheme))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             var parameters = new Dictionary<string, string>(StringComparer.Ordinal);
@@ -1307,7 +1306,7 @@ public static partial class OpenIddictServerOwinHandlers
 
             response.Headers.Append(Headers.WwwAuthenticate, builder.ToString());
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1344,13 +1343,13 @@ public static partial class OpenIddictServerOwinHandlers
             // If the response doesn't contain a WWW-Authenticate header, don't return an empty response.
             if (!response.Headers.ContainsKey(Headers.WwwAuthenticate))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             context.Logger.LogInformation(6141, SR.GetResourceString(SR.ID6141), context.Transaction.Response);
             context.HandleRequest();
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1447,7 +1446,7 @@ public static partial class OpenIddictServerOwinHandlers
 
             if (string.IsNullOrEmpty(context.Transaction.Response.Error))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Don't return the state originally sent by the client application.
@@ -1455,7 +1454,7 @@ public static partial class OpenIddictServerOwinHandlers
 
             context.SkipRequest();
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -1562,7 +1561,7 @@ public static partial class OpenIddictServerOwinHandlers
             context.Logger.LogInformation(6145, SR.GetResourceString(SR.ID6145));
             context.HandleRequest();
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 }

src/OpenIddict.Server/OpenIddictServerBuilder.cs

@@ -13,7 +13,6 @@ using System.Security.Cryptography;
 using System.Security.Cryptography.X509Certificates;
 using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.IdentityModel.Tokens;
-using OpenIddict.Extensions;
 using OpenIddict.Server;
 
 namespace Microsoft.Extensions.DependencyInjection;

src/OpenIddict.Server/OpenIddictServerConfiguration.cs

@@ -11,7 +11,6 @@ using System.Text;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Options;
 using Microsoft.IdentityModel.Tokens;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Server;
 

src/OpenIddict.Server/OpenIddictServerDispatcher.cs

@@ -7,7 +7,6 @@
 using System.ComponentModel;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Server;
 

src/OpenIddict.Server/OpenIddictServerHandlers.Authentication.cs

@@ -11,7 +11,6 @@ using System.Text.Json;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Server;
 
@@ -467,10 +466,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2028(Parameters.Request),
                         uri: SR.FormatID8000(SR.ID2028));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -508,10 +507,10 @@ public static partial class OpenIddictServerHandlers
                             description: SR.FormatID2029(Parameters.RequestUri),
                             uri: SR.FormatID8000(SR.ID2029));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // OpenIddict only supports "request_uri" parameters containing a reference to a request
@@ -527,7 +526,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2028(Parameters.RequestUri),
                         uri: SR.FormatID8000(SR.ID2028));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Both the OpenID Connect core and OAuth 2.0 JWT-Secured Authorization Request specifications
@@ -541,10 +540,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2177(Parameters.ClientId),
                         uri: SR.FormatID8000(SR.ID2177));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -582,10 +581,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2029(Parameters.ClientId),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -677,7 +676,7 @@ public static partial class OpenIddictServerHandlers
                 var value = context.RequestTokenPrincipal?.GetClaim(Claims.Private.RequestParameters);
                 if (string.IsNullOrEmpty(value))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 using var document = JsonDocument.Parse(value);
@@ -695,7 +694,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2178(Parameters.ClientId),
                         uri: SR.FormatID8000(SR.ID2178));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Note: the "request" and "request_uri" parameters have been initially introduced by the OpenID Connect
@@ -717,7 +716,7 @@ public static partial class OpenIddictServerHandlers
                 context.Request = request;
                 context.RedirectUri = request.RedirectUri;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -760,10 +759,10 @@ public static partial class OpenIddictServerHandlers
                             description: SR.FormatID2029(Parameters.RedirectUri),
                             uri: SR.FormatID8000(SR.ID2029));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Note: when specified, redirect_uri MUST be an absolute URI.
@@ -778,7 +777,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2030(Parameters.RedirectUri),
                         uri: SR.FormatID8000(SR.ID2030));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Note: when specified, redirect_uri MUST NOT include a fragment component.
@@ -793,7 +792,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2031(Parameters.RedirectUri),
                         uri: SR.FormatID8000(SR.ID2031));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // To prevent issuer fixation attacks where a malicious client would specify an "iss" parameter
@@ -813,11 +812,11 @@ public static partial class OpenIddictServerHandlers
                             description: SR.FormatID2135(Parameters.RedirectUri, Parameters.Iss),
                             uri: SR.FormatID8000(SR.ID2135));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -854,7 +853,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2029(Parameters.ResponseType),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject code flow requests if the server is not configured to allow the authorization code grant type.
@@ -867,7 +866,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2032(Parameters.ResponseType),
                         uri: SR.FormatID8000(SR.ID2032));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject implicit flow requests if the server is not configured to allow the implicit grant type.
@@ -880,7 +879,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2032(Parameters.ResponseType),
                         uri: SR.FormatID8000(SR.ID2032));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject hybrid flow requests if the server is not configured to allow the authorization code or implicit grant types.
@@ -894,7 +893,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2032(Parameters.ResponseType),
                         uri: SR.FormatID8000(SR.ID2032));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Prevent response_type=none from being used with any other value.
@@ -909,7 +908,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2052(Parameters.ResponseType),
                         uri: SR.FormatID8000(SR.ID2052));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject requests that specify an unsupported response_type.
@@ -923,10 +922,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2032(Parameters.ResponseType),
                         uri: SR.FormatID8000(SR.ID2032));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -966,7 +965,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2033(Parameters.ResponseType, Parameters.ResponseMode),
                         uri: SR.FormatID8000(SR.ID2033));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject requests that specify an unsupported response_mode or don't specify a different response_mode
@@ -980,10 +979,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2032(Parameters.ResponseMode),
                         uri: SR.FormatID8000(SR.ID2032));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
 
                 static bool ValidateResponseMode(OpenIddictRequest request, OpenIddictServerOptions options)
                 {
@@ -1045,7 +1044,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2034(Scopes.OpenId),
                         uri: SR.FormatID8000(SR.ID2034));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject authorization requests that specify scope=offline_access if the refresh token flow is not enabled.
@@ -1056,10 +1055,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2035(Scopes.OfflineAccess),
                         uri: SR.FormatID8000(SR.ID2035));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1095,10 +1094,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2193(Parameters.Audience),
                         uri: SR.FormatID8000(SR.ID2193));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1139,7 +1138,7 @@ public static partial class OpenIddictServerHandlers
                             description: SR.FormatID2030(Parameters.Resource),
                             uri: SR.FormatID8000(SR.ID2030));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
 
                     // Note: resource indicators MUST NOT contain a fragment.
@@ -1152,11 +1151,11 @@ public static partial class OpenIddictServerHandlers
                             description: SR.FormatID2031(Parameters.Resource),
                             uri: SR.FormatID8000(SR.ID2031));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1190,7 +1189,7 @@ public static partial class OpenIddictServerHandlers
 
                 if (!string.IsNullOrEmpty(context.Request.Nonce) || !context.Request.HasScope(Scopes.OpenId))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 if (context.Request.IsImplicitFlow() || context.Request.IsHybridFlow())
@@ -1202,10 +1201,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2029(Parameters.Nonce),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1234,7 +1233,7 @@ public static partial class OpenIddictServerHandlers
 
                 if (string.IsNullOrEmpty(context.Request.Prompt))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject requests specifying an unsupported prompt value.
@@ -1250,7 +1249,7 @@ public static partial class OpenIddictServerHandlers
                             description: SR.FormatID2032(Parameters.Prompt),
                             uri: SR.FormatID8000(SR.ID2032));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
                 }
 
@@ -1267,10 +1266,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2052(Parameters.Prompt),
                         uri: SR.FormatID8000(SR.ID2052));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1310,7 +1309,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2029(Parameters.CodeChallenge),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // At this point, stop validating the PKCE parameters if both the
@@ -1318,7 +1317,7 @@ public static partial class OpenIddictServerHandlers
                 if (string.IsNullOrEmpty(context.Request.CodeChallenge) &&
                     string.IsNullOrEmpty(context.Request.CodeChallengeMethod))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Ensure a code_challenge was specified if a code_challenge_method was used.
@@ -1331,7 +1330,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2037(Parameters.CodeChallengeMethod, Parameters.CodeChallenge),
                         uri: SR.FormatID8000(SR.ID2037));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // If the plain code challenge method was not explicitly enabled,
@@ -1346,7 +1345,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2029(Parameters.CodeChallengeMethod),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // If a code_challenge_method was specified, ensure the algorithm is supported.
@@ -1360,7 +1359,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2032(Parameters.CodeChallengeMethod),
                         uri: SR.FormatID8000(SR.ID2032));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // When code_challenge or code_challenge_method is specified, ensure the response_type includes "code".
@@ -1373,10 +1372,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2040(Parameters.CodeChallenge, Parameters.CodeChallengeMethod, ResponseTypes.Code),
                         uri: SR.FormatID8000(SR.ID2040));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1666,10 +1665,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2190(Parameters.Resource),
                         uri: SR.FormatID8000(SR.ID2190));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -2177,7 +2176,7 @@ public static partial class OpenIddictServerHandlers
 
                 if (context.IdentityTokenHintPrincipal is null)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 Debug.Assert(!string.IsNullOrEmpty(context.ClientId), SR.FormatID4000(Parameters.ClientId));
@@ -2194,10 +2193,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.GetResourceString(SR.ID2141),
                         uri: SR.FormatID8000(SR.ID2141));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -2231,7 +2230,7 @@ public static partial class OpenIddictServerHandlers
 
                 context.IdentityTokenHintPrincipal ??= notification.IdentityTokenHintPrincipal;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -2263,7 +2262,7 @@ public static partial class OpenIddictServerHandlers
                 // redirect_uri, as the user agent will be redirected to the same page.
                 if (context.Request is null || !string.IsNullOrEmpty(context.Response.RequestUri))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 var notification = context.Transaction.GetProperty<ValidateAuthorizationRequestContext>(
@@ -2276,7 +2275,7 @@ public static partial class OpenIddictServerHandlers
                     context.RedirectUri = notification.RedirectUri;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -2306,7 +2305,7 @@ public static partial class OpenIddictServerHandlers
 
                 if (context.Request is null)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 context.ResponseMode = context.Request.ResponseMode;
@@ -2319,7 +2318,7 @@ public static partial class OpenIddictServerHandlers
                                            context.Request.IsQueryResponseMode()    ? ResponseModes.Query    : null;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -2355,7 +2354,7 @@ public static partial class OpenIddictServerHandlers
                     context.Response.State = context.Request?.State;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -2401,7 +2400,7 @@ public static partial class OpenIddictServerHandlers
                     };
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -2720,10 +2719,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2028(Parameters.Request),
                         uri: SR.FormatID8000(SR.ID2028));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -2762,10 +2761,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2074(Parameters.RequestUri),
                         uri: SR.FormatID8000(SR.ID2074));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -2804,10 +2803,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2029(Parameters.ClientId),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -2851,10 +2850,10 @@ public static partial class OpenIddictServerHandlers
                             description: SR.FormatID2029(Parameters.RedirectUri),
                             uri: SR.FormatID8000(SR.ID2029));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Note: when specified, redirect_uri MUST be an absolute URI.
@@ -2869,7 +2868,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2030(Parameters.RedirectUri),
                         uri: SR.FormatID8000(SR.ID2030));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Note: when specified, redirect_uri MUST NOT include a fragment component.
@@ -2884,7 +2883,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2031(Parameters.RedirectUri),
                         uri: SR.FormatID8000(SR.ID2031));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // To prevent issuer fixation attacks where a malicious client would specify an "iss" parameter
@@ -2904,11 +2903,11 @@ public static partial class OpenIddictServerHandlers
                             description: SR.FormatID2135(Parameters.RedirectUri, Parameters.Iss),
                             uri: SR.FormatID8000(SR.ID2135));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -2946,7 +2945,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2029(Parameters.ResponseType),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject code flow requests if the server is not configured to allow the authorization code grant type.
@@ -2959,7 +2958,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2032(Parameters.ResponseType),
                         uri: SR.FormatID8000(SR.ID2032));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject implicit flow requests if the server is not configured to allow the implicit grant type.
@@ -2972,7 +2971,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2032(Parameters.ResponseType),
                         uri: SR.FormatID8000(SR.ID2032));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject hybrid flow requests if the server is not configured to allow the authorization code or implicit grant types.
@@ -2986,7 +2985,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2032(Parameters.ResponseType),
                         uri: SR.FormatID8000(SR.ID2032));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Prevent response_type=none from being used with any other value.
@@ -3001,7 +3000,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2052(Parameters.ResponseType),
                         uri: SR.FormatID8000(SR.ID2052));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject requests that specify an unsupported response_type.
@@ -3015,10 +3014,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2032(Parameters.ResponseType),
                         uri: SR.FormatID8000(SR.ID2032));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -3059,7 +3058,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2033(Parameters.ResponseType, Parameters.ResponseMode),
                         uri: SR.FormatID8000(SR.ID2033));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject requests that specify an unsupported response_mode or don't specify a different response_mode
@@ -3073,10 +3072,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2032(Parameters.ResponseMode),
                         uri: SR.FormatID8000(SR.ID2032));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
 
                 static bool ValidatePushedResponseMode(OpenIddictRequest request, OpenIddictServerOptions options)
                 {
@@ -3139,7 +3138,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2034(Scopes.OpenId),
                         uri: SR.FormatID8000(SR.ID2034));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject pushed authorization requests that specify scope=offline_access if the refresh token flow is not enabled.
@@ -3150,10 +3149,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2035(Scopes.OfflineAccess),
                         uri: SR.FormatID8000(SR.ID2035));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -3189,10 +3188,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2194(Parameters.Audience),
                         uri: SR.FormatID8000(SR.ID2194));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -3233,7 +3232,7 @@ public static partial class OpenIddictServerHandlers
                             description: SR.FormatID2030(Parameters.Resource),
                             uri: SR.FormatID8000(SR.ID2030));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
 
                     // Note: resource indicators MUST NOT contain a fragment.
@@ -3246,11 +3245,11 @@ public static partial class OpenIddictServerHandlers
                             description: SR.FormatID2031(Parameters.Resource),
                             uri: SR.FormatID8000(SR.ID2031));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -3284,7 +3283,7 @@ public static partial class OpenIddictServerHandlers
 
                 if (!string.IsNullOrEmpty(context.Request.Nonce) || !context.Request.HasScope(Scopes.OpenId))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 if (context.Request.IsImplicitFlow() || context.Request.IsHybridFlow())
@@ -3296,10 +3295,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2029(Parameters.Nonce),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -3328,7 +3327,7 @@ public static partial class OpenIddictServerHandlers
 
                 if (string.IsNullOrEmpty(context.Request.Prompt))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject requests specifying an unsupported prompt value.
@@ -3344,7 +3343,7 @@ public static partial class OpenIddictServerHandlers
                             description: SR.FormatID2032(Parameters.Prompt),
                             uri: SR.FormatID8000(SR.ID2032));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
                 }
 
@@ -3361,10 +3360,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2052(Parameters.Prompt),
                         uri: SR.FormatID8000(SR.ID2052));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -3404,7 +3403,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2029(Parameters.CodeChallenge),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // At this point, stop validating the PKCE parameters if both the
@@ -3412,7 +3411,7 @@ public static partial class OpenIddictServerHandlers
                 if (string.IsNullOrEmpty(context.Request.CodeChallenge) &&
                     string.IsNullOrEmpty(context.Request.CodeChallengeMethod))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Ensure a code_challenge was specified if a code_challenge_method was used.
@@ -3425,7 +3424,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2037(Parameters.CodeChallengeMethod, Parameters.CodeChallenge),
                         uri: SR.FormatID8000(SR.ID2037));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // If the plain code challenge method was not explicitly enabled,
@@ -3440,7 +3439,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2029(Parameters.CodeChallengeMethod),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // If a code_challenge_method was specified, ensure the algorithm is supported.
@@ -3454,7 +3453,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2032(Parameters.CodeChallengeMethod),
                         uri: SR.FormatID8000(SR.ID2032));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // When code_challenge or code_challenge_method is specified, ensure the response_type includes "code".
@@ -3467,10 +3466,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2040(Parameters.CodeChallenge, Parameters.CodeChallengeMethod, ResponseTypes.Code),
                         uri: SR.FormatID8000(SR.ID2040));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -3821,10 +3820,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2190(Parameters.Resource),
                         uri: SR.FormatID8000(SR.ID2190));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -4262,7 +4261,7 @@ public static partial class OpenIddictServerHandlers
 
                 if (context.IdentityTokenHintPrincipal is null)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 Debug.Assert(!string.IsNullOrEmpty(context.ClientId), SR.FormatID4000(Parameters.ClientId));
@@ -4279,10 +4278,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.GetResourceString(SR.ID2141),
                         uri: SR.FormatID8000(SR.ID2141));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -4316,7 +4315,7 @@ public static partial class OpenIddictServerHandlers
 
                 context.IdentityTokenHintPrincipal ??= notification.IdentityTokenHintPrincipal;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Server/OpenIddictServerHandlers.Device.cs

@@ -10,7 +10,6 @@ using System.Security.Claims;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Server;
 
@@ -363,10 +362,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2035(Scopes.OfflineAccess),
                         uri: SR.FormatID8000(SR.ID2035));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -402,7 +401,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2037(Parameters.ClientAssertionType, Parameters.ClientAssertion),
                         uri: SR.FormatID8000(SR.ID2037));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Ensure a client_assertion is specified when a client_assertion_type was attached.
@@ -414,7 +413,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2037(Parameters.ClientAssertion, Parameters.ClientAssertionType),
                         uri: SR.FormatID8000(SR.ID2037));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject requests that use multiple client authentication methods.
@@ -430,7 +429,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.GetResourceString(SR.ID2087),
                         uri: SR.FormatID8000(SR.ID2087));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Ensure the specified client_assertion_type is supported.
@@ -442,10 +441,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2032(Parameters.ClientAssertionType),
                         uri: SR.FormatID8000(SR.ID2032));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1135,7 +1134,7 @@ public static partial class OpenIddictServerHandlers
 
                 context.UserCodePrincipal ??= notification.UserCodePrincipal;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Server/OpenIddictServerHandlers.Discovery.cs

@@ -10,7 +10,6 @@ using System.Security.Cryptography;
 using System.Text.Json;
 using Microsoft.Extensions.Logging;
 using Microsoft.IdentityModel.Tokens;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Server;
 
@@ -351,7 +350,7 @@ public static partial class OpenIddictServerHandlers
                     _ => throw new InvalidOperationException(SR.GetResourceString(SR.ID0496))
                 };
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -408,7 +407,7 @@ public static partial class OpenIddictServerHandlers
                 context.UserInfoEndpoint ??= OpenIddictHelpers.CreateAbsoluteUri(
                     context.BaseUri, context.Options.UserInfoEndpointUris.FirstOrDefault());
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -437,7 +436,7 @@ public static partial class OpenIddictServerHandlers
 
                 context.GrantTypes.UnionWith(context.Options.GrantTypes);
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -466,7 +465,7 @@ public static partial class OpenIddictServerHandlers
 
                 context.ResponseTypes.UnionWith(context.Options.ResponseTypes);
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -496,7 +495,7 @@ public static partial class OpenIddictServerHandlers
                 // Only include the response modes if at least one response type is returned.
                 if (context.ResponseTypes.Count is 0)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Note: returning an access or identity token using the query response mode is explicitly disallowed.
@@ -514,7 +513,7 @@ public static partial class OpenIddictServerHandlers
                 context.ResponseModes.UnionWith(context.Options.ResponseModes.Where(
                     static mode => mode is not ResponseModes.Query));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -571,7 +570,7 @@ public static partial class OpenIddictServerHandlers
                     context.TokenEndpointAuthenticationMethods.UnionWith(context.Options.ClientAuthenticationMethods);
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -605,7 +604,7 @@ public static partial class OpenIddictServerHandlers
                     context.CodeChallengeMethods.UnionWith(context.Options.CodeChallengeMethods);
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -634,7 +633,7 @@ public static partial class OpenIddictServerHandlers
 
                 context.Scopes.UnionWith(context.Options.Scopes);
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -663,7 +662,7 @@ public static partial class OpenIddictServerHandlers
 
                 context.Claims.UnionWith(context.Options.Claims);
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -692,7 +691,7 @@ public static partial class OpenIddictServerHandlers
 
                 context.SubjectTypes.UnionWith(context.Options.SubjectTypes);
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -721,7 +720,7 @@ public static partial class OpenIddictServerHandlers
 
                 context.PromptValues.UnionWith(context.Options.PromptValues);
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -787,7 +786,7 @@ public static partial class OpenIddictServerHandlers
                     context.IdTokenSigningAlgorithms.Add(algorithm);
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -816,7 +815,7 @@ public static partial class OpenIddictServerHandlers
 
                 context.RequirePushedAuthorizationRequests = context.Options.RequirePushedAuthorizationRequests;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -855,7 +854,7 @@ public static partial class OpenIddictServerHandlers
                 // see https://datatracker.ietf.org/doc/html/draft-ietf-oauth-iss-auth-resp-05.
                 context.Metadata[Metadata.AuthorizationResponseIssParameterSupported] = true;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1343,7 +1342,7 @@ public static partial class OpenIddictServerHandlers
                     context.Keys.Add(key);
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Server/OpenIddictServerHandlers.Exchange.cs

@@ -13,7 +13,6 @@ using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Microsoft.IdentityModel.Tokens;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Server;
 
@@ -376,7 +375,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2029(Parameters.GrantType),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject token requests that don't specify a supported grant type.
@@ -389,7 +388,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2032(Parameters.GrantType),
                         uri: SR.FormatID8000(SR.ID2032));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject token requests that specify scope=offline_access if the refresh token flow is not enabled.
@@ -401,10 +400,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2035(Scopes.OfflineAccess),
                         uri: SR.FormatID8000(SR.ID2035));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -447,7 +446,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2029(Parameters.ClientId),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject grant_type=client_credentials requests that don't specify a client_id or a client_assertion.
@@ -464,10 +463,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2029(Parameters.ClientId),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -506,10 +505,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2029(Parameters.Code),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -545,7 +544,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2037(Parameters.ClientAssertionType, Parameters.ClientAssertion),
                         uri: SR.FormatID8000(SR.ID2037));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Ensure a client_assertion is specified when a client_assertion_type was attached.
@@ -557,7 +556,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2037(Parameters.ClientAssertion, Parameters.ClientAssertionType),
                         uri: SR.FormatID8000(SR.ID2037));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject requests that use multiple client authentication methods.
@@ -573,7 +572,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.GetResourceString(SR.ID2087),
                         uri: SR.FormatID8000(SR.ID2087));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Ensure the specified client_assertion_type is supported.
@@ -585,7 +584,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2032(Parameters.ClientAssertionType),
                         uri: SR.FormatID8000(SR.ID2032));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject grant_type=client_credentials requests missing the client credentials.
@@ -600,10 +599,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2057(Parameters.ClientSecret, Parameters.ClientAssertion),
                         uri: SR.FormatID8000(SR.ID2057));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -640,10 +639,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2058(Parameters.DeviceCode),
                         uri: SR.FormatID8000(SR.ID2058));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -682,10 +681,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2029(Parameters.RefreshToken),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -715,7 +714,7 @@ public static partial class OpenIddictServerHandlers
 
                 if (!context.Request.IsTokenExchangeGrantType())
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject token exchange requests missing the mandatory subject token.
@@ -730,7 +729,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2029(Parameters.SubjectToken),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject token exchange requests missing the mandatory subject token type.
@@ -743,7 +742,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2029(Parameters.SubjectTokenType),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject token exchange requests that specify an actor token but don't include an actor token type.
@@ -757,7 +756,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2037(Parameters.ActorToken, Parameters.ActorTokenType),
                         uri: SR.FormatID8000(SR.ID2037));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject token exchange requests that specify an actor token type but don't include an actor token.
@@ -771,7 +770,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2037(Parameters.ActorTokenType, Parameters.ActorToken),
                         uri: SR.FormatID8000(SR.ID2037));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject token exchange requests that specify an unsupported subject token type.
@@ -782,7 +781,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2032(Parameters.SubjectTokenType),
                         uri: SR.FormatID8000(SR.ID2032));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject token exchange requests that specify an unsupported actor token type.
@@ -794,7 +793,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2032(Parameters.ActorTokenType),
                         uri: SR.FormatID8000(SR.ID2032));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject token exchange requests that specify an unsupported requested token type.
@@ -806,10 +805,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2032(Parameters.RequestedTokenType),
                         uri: SR.FormatID8000(SR.ID2032));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -849,10 +848,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2059(Parameters.Username, Parameters.Password),
                         uri: SR.FormatID8000(SR.ID2059));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -881,7 +880,7 @@ public static partial class OpenIddictServerHandlers
 
                 if (!context.Request.IsAuthorizationCodeGrantType())
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Optimization: the ValidateCodeVerifier event handler automatically rejects grant_type=authorization_code
@@ -897,10 +896,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2029(Parameters.CodeVerifier),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -944,10 +943,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2074(Parameters.Scope),
                         uri: SR.FormatID8000(SR.ID2074));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -976,7 +975,7 @@ public static partial class OpenIddictServerHandlers
 
                 if (context.Request.Audiences is null or [])
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Prevent audiences parameters from being attached to token requests that don't use the
@@ -990,10 +989,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2195(Parameters.Audience),
                         uri: SR.FormatID8000(SR.ID2195));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1034,7 +1033,7 @@ public static partial class OpenIddictServerHandlers
                             description: SR.FormatID2030(Parameters.Resource),
                             uri: SR.FormatID8000(SR.ID2030));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
 
                     // Note: resource indicators MUST NOT contain a fragment.
@@ -1047,11 +1046,11 @@ public static partial class OpenIddictServerHandlers
                             description: SR.FormatID2031(Parameters.Resource),
                             uri: SR.FormatID8000(SR.ID2031));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1171,10 +1170,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2190(Parameters.Audience),
                         uri: SR.FormatID8000(SR.ID2190));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1215,10 +1214,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2190(Parameters.Resource),
                         uri: SR.FormatID8000(SR.ID2190));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1715,7 +1714,7 @@ public static partial class OpenIddictServerHandlers
                         //
                         // See https://tools.ietf.org/html/rfc6749#section-6
                         // and http://openid.net/specs/openid-connect-core-1_0.html#RefreshingAccessToken for more information.
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
 
                     // If at least one presenter was associated to the authorization code/device code/refresh token,
@@ -1739,7 +1738,7 @@ public static partial class OpenIddictServerHandlers
                                              _               => SR.FormatID8000(SR.ID2068)
                             });
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
 
                     // Ensure the authorization code/device code/refresh token was issued to the client making the token request.
@@ -1762,7 +1761,7 @@ public static partial class OpenIddictServerHandlers
                                              _               => SR.FormatID8000(SR.ID2071)
                             });
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
                 }
 
@@ -1791,7 +1790,7 @@ public static partial class OpenIddictServerHandlers
                                     description: SR.GetResourceString(SR.ID2186),
                                     uri: SR.FormatID8000(SR.ID2186));
 
-                                return default;
+                                return ValueTask.CompletedTask;
                             }
 
                             // Reject the request if the caller is neither a valid audience nor a valid presenter.
@@ -1805,7 +1804,7 @@ public static partial class OpenIddictServerHandlers
                                     description: SR.GetResourceString(SR.ID2187),
                                     uri: SR.FormatID8000(SR.ID2187));
 
-                                return default;
+                                return ValueTask.CompletedTask;
                             }
 
                             break;
@@ -1830,7 +1829,7 @@ public static partial class OpenIddictServerHandlers
                                     description: SR.GetResourceString(SR.ID2186),
                                     uri: SR.FormatID8000(SR.ID2186));
 
-                                return default;
+                                return ValueTask.CompletedTask;
                             }
 
                             // Reject the request if the caller is not a valid presenter.
@@ -1843,7 +1842,7 @@ public static partial class OpenIddictServerHandlers
                                     description: SR.GetResourceString(SR.ID2187),
                                     uri: SR.FormatID8000(SR.ID2187));
 
-                                return default;
+                                return ValueTask.CompletedTask;
                             }
 
                             break;
@@ -1877,7 +1876,7 @@ public static partial class OpenIddictServerHandlers
                                     description: SR.GetResourceString(SR.ID2188),
                                     uri: SR.FormatID8000(SR.ID2188));
 
-                                return default;
+                                return ValueTask.CompletedTask;
                             }
 
                             // Reject the request if the caller is neither a valid audience nor a valid presenter.
@@ -1891,7 +1890,7 @@ public static partial class OpenIddictServerHandlers
                                     description: SR.GetResourceString(SR.ID2189),
                                     uri: SR.FormatID8000(SR.ID2189));
 
-                                return default;
+                                return ValueTask.CompletedTask;
                             }
 
                             break;
@@ -1916,7 +1915,7 @@ public static partial class OpenIddictServerHandlers
                                     description: SR.GetResourceString(SR.ID2188),
                                     uri: SR.FormatID8000(SR.ID2188));
 
-                                return default;
+                                return ValueTask.CompletedTask;
                             }
 
                             // Reject the request if the caller is not a valid presenter.
@@ -1929,7 +1928,7 @@ public static partial class OpenIddictServerHandlers
                                     description: SR.GetResourceString(SR.ID2189),
                                     uri: SR.FormatID8000(SR.ID2189));
 
-                                return default;
+                                return ValueTask.CompletedTask;
                             }
 
                             break;
@@ -1941,7 +1940,7 @@ public static partial class OpenIddictServerHandlers
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1970,7 +1969,7 @@ public static partial class OpenIddictServerHandlers
 
                 if (!context.Request.IsAuthorizationCodeGrantType())
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 Debug.Assert(context.AuthorizationCodePrincipal is { Identity: ClaimsIdentity }, SR.GetResourceString(SR.ID4006));
@@ -1985,7 +1984,7 @@ public static partial class OpenIddictServerHandlers
                 var uri = context.AuthorizationCodePrincipal.GetClaim(Claims.Private.RedirectUri);
                 if (string.IsNullOrEmpty(uri))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 if (string.IsNullOrEmpty(context.Request.RedirectUri))
@@ -1997,7 +1996,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2029(Parameters.RedirectUri),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 if (!string.Equals(uri, context.Request.RedirectUri, StringComparison.Ordinal))
@@ -2009,10 +2008,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2072(Parameters.RedirectUri),
                         uri: SR.FormatID8000(SR.ID2072));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -2041,7 +2040,7 @@ public static partial class OpenIddictServerHandlers
 
                 if (!context.Request.IsAuthorizationCodeGrantType())
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 Debug.Assert(context.AuthorizationCodePrincipal is { Identity: ClaimsIdentity }, SR.GetResourceString(SR.ID4006));
@@ -2066,10 +2065,10 @@ public static partial class OpenIddictServerHandlers
                             description: SR.FormatID2073(Parameters.CodeVerifier, Parameters.CodeChallenge),
                             uri: SR.FormatID8000(SR.ID2073));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Get the code verifier from the token request. If it cannot be found, return an invalid_grant error.
@@ -2082,7 +2081,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2029(Parameters.CodeVerifier),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 var comparand = context.AuthorizationCodePrincipal.GetClaim(Claims.Private.CodeChallengeMethod) switch
@@ -2112,10 +2111,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2052(Parameters.CodeVerifier),
                         uri: SR.FormatID8000(SR.ID2052));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -2145,7 +2144,7 @@ public static partial class OpenIddictServerHandlers
 
                 if (string.IsNullOrEmpty(context.Request.Scope) || !context.Request.IsRefreshTokenGrantType())
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 Debug.Assert(context.RefreshTokenPrincipal is { Identity: ClaimsIdentity }, SR.GetResourceString(SR.ID4006));
@@ -2163,7 +2162,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2074(Parameters.Scope),
                         uri: SR.FormatID8000(SR.ID2074));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // When an explicit scope parameter has been included in the token request,
@@ -2179,10 +2178,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2052(Parameters.Scope),
                         uri: SR.FormatID8000(SR.ID2052));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -2215,7 +2214,7 @@ public static partial class OpenIddictServerHandlers
                     !context.Request.IsRefreshTokenGrantType() &&
                     !context.Request.IsTokenExchangeGrantType())
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 var notification = context.Transaction.GetProperty<ValidateTokenRequestContext>(
@@ -2247,7 +2246,7 @@ public static partial class OpenIddictServerHandlers
                     _ => null
                 };
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -2276,7 +2275,7 @@ public static partial class OpenIddictServerHandlers
 
                 if (string.IsNullOrEmpty(context.Error))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // If the error indicates an invalid token, return a standard invalid_grant.
@@ -2286,7 +2285,7 @@ public static partial class OpenIddictServerHandlers
                                                  context.Request.IsRefreshTokenGrantType() ||
                                                  context.Request.IsTokenExchangeGrantType()))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 context.Response.Error = context.Error switch
@@ -2300,7 +2299,7 @@ public static partial class OpenIddictServerHandlers
                     _ => context.Error // Otherwise, keep the error as-is.
                 };
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Server/OpenIddictServerHandlers.Introspection.cs

@@ -362,10 +362,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2029(Parameters.Token),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -401,7 +401,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2037(Parameters.ClientAssertionType, Parameters.ClientAssertion),
                         uri: SR.FormatID8000(SR.ID2037));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Ensure a client_assertion is specified when a client_assertion_type was attached.
@@ -413,7 +413,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2037(Parameters.ClientAssertion, Parameters.ClientAssertionType),
                         uri: SR.FormatID8000(SR.ID2037));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject requests that use multiple client authentication methods.
@@ -429,7 +429,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.GetResourceString(SR.ID2087),
                         uri: SR.FormatID8000(SR.ID2087));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Ensure the specified client_assertion_type is supported.
@@ -441,10 +441,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2032(Parameters.ClientAssertionType),
                         uri: SR.FormatID8000(SR.ID2032));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -599,10 +599,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.GetResourceString(SR.ID2076),
                         uri: SR.FormatID8000(SR.ID2076));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -652,7 +652,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.GetResourceString(SR.ID2077),
                         uri: SR.FormatID8000(SR.ID2077));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // When the introspected token is a refresh token, the caller must be
@@ -669,10 +669,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.GetResourceString(SR.ID2077),
                         uri: SR.FormatID8000(SR.ID2077));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -708,7 +708,7 @@ public static partial class OpenIddictServerHandlers
 
                 context.GenericTokenPrincipal ??= notification.GenericTokenPrincipal;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -776,7 +776,7 @@ public static partial class OpenIddictServerHandlers
                     context.TokenType = TokenTypes.Bearer;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -973,7 +973,7 @@ public static partial class OpenIddictServerHandlers
 
                 if (string.IsNullOrEmpty(context.Error))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // If the error indicates an invalid token, remove the error details and only return active: false,
@@ -990,7 +990,7 @@ public static partial class OpenIddictServerHandlers
                     context.Response[Claims.Active] = false;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Server/OpenIddictServerHandlers.Protection.cs

@@ -13,7 +13,6 @@ using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Microsoft.IdentityModel.JsonWebTokens;
 using Microsoft.IdentityModel.Tokens;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Server;
 
@@ -264,7 +263,7 @@ public static partial class OpenIddictServerHandlers
                 context.SecurityTokenHandler = context.Options.JsonWebTokenHandler;
                 context.TokenValidationParameters = parameters;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -294,7 +293,7 @@ public static partial class OpenIddictServerHandlers
                 // If no character was explicitly added, all characters are considered valid.
                 if (context.AllowedCharset.Count is 0)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Remove the disallowed characters from the token string. If the token is
@@ -307,12 +306,12 @@ public static partial class OpenIddictServerHandlers
                         description: SR.GetResourceString(SR.ID2004),
                         uri: SR.FormatID8000(SR.ID2004));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 context.Token = token;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -632,7 +631,7 @@ public static partial class OpenIddictServerHandlers
 
                 if (context.Principal is null)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Note: in previous OpenIddict versions, scopes were represented as a JSON array
@@ -648,7 +647,7 @@ public static partial class OpenIddictServerHandlers
                     context.Principal.SetClaim(Claims.Scope, string.Join(" ", scopes));
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -677,7 +676,7 @@ public static partial class OpenIddictServerHandlers
 
                 if (context.Principal is null)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // To reduce the size of tokens, some of the private claims used by OpenIddict
@@ -751,7 +750,7 @@ public static partial class OpenIddictServerHandlers
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -906,7 +905,7 @@ public static partial class OpenIddictServerHandlers
                         });
 
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // When using JWT or Data Protection tokens, the correct token type is always enforced by IdentityModel
@@ -924,7 +923,7 @@ public static partial class OpenIddictServerHandlers
                     throw new InvalidOperationException(SR.FormatID0005(type, string.Join(", ", context.ValidTokenTypes)));
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -981,10 +980,10 @@ public static partial class OpenIddictServerHandlers
                             _ => SR.FormatID8000(SR.ID2019)
                         });
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1017,7 +1016,7 @@ public static partial class OpenIddictServerHandlers
                 // If no specific value is expected, skip the default presenter validation.
                 if (context.ValidPresenters.Count is 0)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // If the token doesn't have any presenter attached, return an error.
@@ -1031,7 +1030,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.GetResourceString(SR.ID2184),
                         uri: SR.FormatID8000(SR.ID2184));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // If the token doesn't include any registered presenter, return an error.
@@ -1044,10 +1043,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.GetResourceString(SR.ID2185),
                         uri: SR.FormatID8000(SR.ID2185));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1080,7 +1079,7 @@ public static partial class OpenIddictServerHandlers
                 // If no specific value is expected, skip the default audience validation.
                 if (context.ValidAudiences.Count is 0)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // If the token doesn't have any audience attached, return an error.
@@ -1094,7 +1093,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.GetResourceString(SR.ID2093),
                         uri: SR.FormatID8000(SR.ID2093));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // If the token doesn't include any registered audience, return an error.
@@ -1107,10 +1106,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.GetResourceString(SR.ID2094),
                         uri: SR.FormatID8000(SR.ID2094));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1409,7 +1408,7 @@ public static partial class OpenIddictServerHandlers
                     _ => context.Options.SigningCredentials.First()
                 };
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1552,7 +1551,7 @@ public static partial class OpenIddictServerHandlers
 
                 context.SecurityTokenDescriptor.Subject = (ClaimsIdentity) principal.Identity;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1668,7 +1667,7 @@ public static partial class OpenIddictServerHandlers
                     string value => value
                 };
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1699,7 +1698,7 @@ public static partial class OpenIddictServerHandlers
                 // If a token was already attached by another handler, don't overwrite it.
                 if (!string.IsNullOrEmpty(context.Token))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 context.Token = context.SecurityTokenHandler.CreateToken(context.SecurityTokenDescriptor);
@@ -1707,7 +1706,7 @@ public static partial class OpenIddictServerHandlers
                 context.Logger.LogTrace(6013, SR.GetResourceString(SR.ID6013), context.TokenType,
                     context.Token, context.SecurityTokenDescriptor.Subject?.Claims ?? []);
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 

src/OpenIddict.Server/OpenIddictServerHandlers.Revocation.cs

@@ -309,10 +309,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2029(Parameters.Token),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -348,7 +348,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2037(Parameters.ClientAssertionType, Parameters.ClientAssertion),
                         uri: SR.FormatID8000(SR.ID2037));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Ensure a client_assertion is specified when a client_assertion_type was attached.
@@ -360,7 +360,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2037(Parameters.ClientAssertion, Parameters.ClientAssertionType),
                         uri: SR.FormatID8000(SR.ID2037));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Reject requests that use multiple client authentication methods.
@@ -376,7 +376,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.GetResourceString(SR.ID2087),
                         uri: SR.FormatID8000(SR.ID2087));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Ensure the specified client_assertion_type is supported.
@@ -388,10 +388,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2032(Parameters.ClientAssertionType),
                         uri: SR.FormatID8000(SR.ID2032));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -546,10 +546,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.GetResourceString(SR.ID2079),
                         uri: SR.FormatID8000(SR.ID2079));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -599,7 +599,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.GetResourceString(SR.ID2080),
                         uri: SR.FormatID8000(SR.ID2080));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // When the revoked token is a refresh token, the caller must be
@@ -616,10 +616,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.GetResourceString(SR.ID2080),
                         uri: SR.FormatID8000(SR.ID2080));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -655,7 +655,7 @@ public static partial class OpenIddictServerHandlers
 
                 context.GenericTokenPrincipal ??= notification.GenericTokenPrincipal;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -758,7 +758,7 @@ public static partial class OpenIddictServerHandlers
 
                 if (string.IsNullOrEmpty(context.Error))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // If the error indicates an invalid token, remove the error details, as required by the revocation
@@ -773,7 +773,7 @@ public static partial class OpenIddictServerHandlers
                     context.Response.ErrorUri = null;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Server/OpenIddictServerHandlers.Session.cs

@@ -12,7 +12,6 @@ using System.Text.Json;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Server;
 
@@ -389,7 +388,7 @@ public static partial class OpenIddictServerHandlers
 
                 if (string.IsNullOrEmpty(context.Request.RequestUri))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // OpenIddict only supports "request_uri" parameters containing a reference to a request token
@@ -402,13 +401,13 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2028(Parameters.RequestUri),
                         uri: SR.FormatID8000(SR.ID2028));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Note: unlike authorization requests, the client_id parameter is not required for end
                 // session requests and may not be present in the original request before it is cached.
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -437,7 +436,7 @@ public static partial class OpenIddictServerHandlers
 
                 if (string.IsNullOrEmpty(context.PostLogoutRedirectUri))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // If an optional post_logout_redirect_uri was provided, validate it.
@@ -450,7 +449,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2030(Parameters.PostLogoutRedirectUri),
                         uri: SR.FormatID8000(SR.ID2030));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 if (!string.IsNullOrEmpty(uri.Fragment))
@@ -462,10 +461,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2031(Parameters.PostLogoutRedirectUri),
                         uri: SR.FormatID8000(SR.ID2031));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -557,7 +556,7 @@ public static partial class OpenIddictServerHandlers
                 var value = context.RequestTokenPrincipal?.GetClaim(Claims.Private.RequestParameters);
                 if (string.IsNullOrEmpty(value))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 using var document = JsonDocument.Parse(value);
@@ -569,7 +568,7 @@ public static partial class OpenIddictServerHandlers
                 context.Request = request;
                 context.PostLogoutRedirectUri = request.PostLogoutRedirectUri;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -947,7 +946,7 @@ public static partial class OpenIddictServerHandlers
 
                 context.IdentityTokenHintPrincipal ??= notification.IdentityTokenHintPrincipal;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -979,7 +978,7 @@ public static partial class OpenIddictServerHandlers
                 // post_logout_redirect_uri, as the user agent will be redirected to the same page.
                 if (context.Request is null || !string.IsNullOrEmpty(context.Response.RequestUri))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 var notification = context.Transaction.GetProperty<ValidateEndSessionRequestContext>(
@@ -992,7 +991,7 @@ public static partial class OpenIddictServerHandlers
                     context.PostLogoutRedirectUri = notification.PostLogoutRedirectUri;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1028,7 +1027,7 @@ public static partial class OpenIddictServerHandlers
                     context.Response.State = context.Request?.State;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Server/OpenIddictServerHandlers.Userinfo.cs

@@ -336,10 +336,10 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2029(Parameters.AccessToken),
                         uri: SR.FormatID8000(SR.ID2029));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -436,7 +436,7 @@ public static partial class OpenIddictServerHandlers
 
                 context.AccessTokenPrincipal ??= notification.AccessTokenPrincipal;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -470,7 +470,7 @@ public static partial class OpenIddictServerHandlers
                 // See http://openid.net/specs/openid-connect-core-1_0.html#UserInfoResponse
                 context.Audiences.UnionWith(context.AccessTokenPrincipal.GetPresenters());
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -529,7 +529,7 @@ public static partial class OpenIddictServerHandlers
                     context.PhoneNumber = context.AccessTokenPrincipal.GetClaim(Claims.PhoneNumber);
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Server/OpenIddictServerHandlers.cs

@@ -16,7 +16,6 @@ using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Microsoft.IdentityModel.JsonWebTokens;
 using Microsoft.IdentityModel.Tokens;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Server;
 
@@ -159,7 +158,7 @@ public static partial class OpenIddictServerHandlers
             // If the base or request URIs couldn't be resolved, don't try to infer the endpoint type.
             if (context is not { BaseUri.IsAbsoluteUri: true, RequestUri.IsAbsoluteUri: true })
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             context.EndpointType =
@@ -181,7 +180,7 @@ public static partial class OpenIddictServerHandlers
                 context.Logger.LogInformation(6053, SR.GetResourceString(SR.ID6053), context.EndpointType);
             }
 
-            return default;
+            return ValueTask.CompletedTask;
 
             bool Matches(IReadOnlyList<Uri> candidates)
             {
@@ -430,7 +429,7 @@ public static partial class OpenIddictServerHandlers
                 _ => (false, false, false, false)
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -560,7 +559,7 @@ public static partial class OpenIddictServerHandlers
                 _ => null
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -606,10 +605,10 @@ public static partial class OpenIddictServerHandlers
                     description: SR.GetResourceString(SR.ID2000),
                     uri: SR.FormatID8000(SR.ID2000));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -731,7 +730,7 @@ public static partial class OpenIddictServerHandlers
                     description: SR.FormatID2171(group.Key),
                     uri: SR.FormatID8000(SR.ID2171));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Client assertions MUST contain an "iss" claim. For more information,
@@ -744,7 +743,7 @@ public static partial class OpenIddictServerHandlers
                     description: SR.FormatID2172(Claims.Issuer),
                     uri: SR.FormatID8000(SR.ID2172));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Client assertions MUST contain a "sub" claim. For more information,
@@ -757,7 +756,7 @@ public static partial class OpenIddictServerHandlers
                     description: SR.FormatID2172(Claims.Subject),
                     uri: SR.FormatID8000(SR.ID2172));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Client assertions MUST contain an "aud" claim. For more information,
@@ -770,7 +769,7 @@ public static partial class OpenIddictServerHandlers
                     description: SR.FormatID2172(Claims.Audience),
                     uri: SR.FormatID8000(SR.ID2172));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Client assertions MUST contain contain a "exp" claim. For more information,
@@ -783,10 +782,10 @@ public static partial class OpenIddictServerHandlers
                     description: SR.FormatID2172(Claims.ExpiresAt),
                     uri: SR.FormatID8000(SR.ID2172));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
 
             static bool ValidateClaimGroup(string name, List<Claim> values) => name switch
             {
@@ -851,7 +850,7 @@ public static partial class OpenIddictServerHandlers
                     description: SR.FormatID2173(Claims.Subject),
                     uri: SR.FormatID8000(SR.ID2173));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // If a client identifier was also specified in the request, ensure the
@@ -865,7 +864,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2173(Claims.Issuer),
                         uri: SR.FormatID8000(SR.ID2173));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 if (!string.Equals(context.ClientId, subject, StringComparison.Ordinal))
@@ -875,7 +874,7 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2173(Claims.Subject),
                         uri: SR.FormatID8000(SR.ID2173));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
             }
 
@@ -885,7 +884,7 @@ public static partial class OpenIddictServerHandlers
                 request.ClientId = context.ClientAssertionPrincipal.GetClaim(Claims.Issuer);
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -930,7 +929,7 @@ public static partial class OpenIddictServerHandlers
                     description: SR.FormatID2172(Claims.Audience),
                     uri: SR.FormatID8000(SR.ID2172));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Throw an exception if the issuer cannot be retrieved or is not valid.
@@ -947,10 +946,10 @@ public static partial class OpenIddictServerHandlers
                     description: SR.FormatID2173(Claims.Audience),
                     uri: SR.FormatID8000(SR.ID2173));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
 
             static bool UriEquals(Uri left, Uri right)
             {
@@ -1379,13 +1378,13 @@ public static partial class OpenIddictServerHandlers
                         description: SR.FormatID2182(Parameters.RequestUri),
                         uri: SR.FormatID8000(SR.ID2182));
 
-                    return default;
+                    return ValueTask.CompletedTask;
 
                 // For other endpoints that don't natively support request tokens, don't return an error
                 // to allow custom implementations to use request tokens with other types of endpoints.
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -2244,7 +2243,7 @@ public static partial class OpenIddictServerHandlers
                 }
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -2316,7 +2315,7 @@ public static partial class OpenIddictServerHandlers
                 }
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -2352,7 +2351,7 @@ public static partial class OpenIddictServerHandlers
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0006));
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -2418,7 +2417,7 @@ public static partial class OpenIddictServerHandlers
                 _ => throw new InvalidOperationException(SR.GetResourceString(SR.ID0006))
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -2572,7 +2571,7 @@ public static partial class OpenIddictServerHandlers
                 }
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -2666,7 +2665,7 @@ public static partial class OpenIddictServerHandlers
                 throw new InvalidOperationException(SR.FormatID0424(group.Key));
             }
 
-            return default;
+            return ValueTask.CompletedTask;
 
             static bool ValidateClaimGroup(string name, List<Claim> values) => name switch
             {
@@ -2882,7 +2881,7 @@ public static partial class OpenIddictServerHandlers
                 case OpenIddictServerEndpointType.Token when context.Request.IsRefreshTokenGrantType():
                     break;
 
-                default: return default;
+                default: return ValueTask.CompletedTask;
             }
 
             var identity = (ClaimsIdentity) context.Principal.Identity;
@@ -2909,7 +2908,7 @@ public static partial class OpenIddictServerHandlers
 
             if (principal is null)
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Restore the internal claims resolved from the token.
@@ -2933,7 +2932,7 @@ public static partial class OpenIddictServerHandlers
                 identity.AddClaims(claims);
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -2964,7 +2963,7 @@ public static partial class OpenIddictServerHandlers
 
             context.Principal.SetClaim(Claims.Private.HostProperties, context.Properties);
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -3001,7 +3000,7 @@ public static partial class OpenIddictServerHandlers
                 context.Principal.SetScopes(Scopes.OpenId);
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -3037,7 +3036,7 @@ public static partial class OpenIddictServerHandlers
                 context.Principal.SetPresenters(context.ClientId);
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -3075,7 +3074,7 @@ public static partial class OpenIddictServerHandlers
             // Reset the audiences collection, as it's set later, based on the token type.
             context.Principal.SetAudiences([]);
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -3253,7 +3252,7 @@ public static partial class OpenIddictServerHandlers
                 _ => (false, false)
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -5050,7 +5049,7 @@ public static partial class OpenIddictServerHandlers
                 context.UserCodePrincipal.SetClaim(Claims.Private.DeviceCodeId, identifier);
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -5161,7 +5160,7 @@ public static partial class OpenIddictServerHandlers
 
             if (string.IsNullOrEmpty(context.AccessToken) && string.IsNullOrEmpty(context.AuthorizationCode))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             var credentials = context.Options.SigningCredentials.Find(
@@ -5186,7 +5185,7 @@ public static partial class OpenIddictServerHandlers
                 context.IdentityTokenPrincipal.SetClaim(Claims.CodeHash, Base64UrlEncoder.Encode(digest, 0, digest.Length / 2));
             }
 
-            return default;
+            return ValueTask.CompletedTask;
 
             static byte[] ComputeTokenHash(SigningCredentials credentials, string token) => credentials switch
             {
@@ -5412,7 +5411,7 @@ public static partial class OpenIddictServerHandlers
                 }
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -5577,7 +5576,7 @@ public static partial class OpenIddictServerHandlers
                 };
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -5613,7 +5612,7 @@ public static partial class OpenIddictServerHandlers
                 }
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -5646,7 +5645,7 @@ public static partial class OpenIddictServerHandlers
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0024));
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -5748,7 +5747,7 @@ public static partial class OpenIddictServerHandlers
                 }
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -5779,7 +5778,7 @@ public static partial class OpenIddictServerHandlers
             context.Response.ErrorDescription = context.ErrorDescription;
             context.Response.ErrorUri = context.ErrorUri;
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -5815,7 +5814,7 @@ public static partial class OpenIddictServerHandlers
                 }
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 }

src/OpenIddict.Validation.AspNetCore/OpenIddictValidationAspNetCoreHandlers.cs

@@ -103,7 +103,7 @@ public static partial class OpenIddictValidationAspNetCoreHandlers
             context.BaseUri = CreateUri(UriHelper.BuildAbsolute(request.Scheme, host, request.PathBase));
             context.RequestUri = CreateUri(UriHelper.BuildAbsolute(request.Scheme, host, request.PathBase, request.Path, request.QueryString));
 
-            return default;
+            return ValueTask.CompletedTask;
 
             // Note: the BCL System.Uri class has strict rules (e.g it rejects specific characters and enforces a
             // limit of 65519 characters for the complete URI representation). To ensure no exception is thrown if the
@@ -150,10 +150,10 @@ public static partial class OpenIddictValidationAspNetCoreHandlers
                     description: SR.FormatID2081(HeaderNames.Host),
                     uri: SR.FormatID8000(SR.ID2081));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -187,7 +187,7 @@ public static partial class OpenIddictValidationAspNetCoreHandlers
             // If a token was already resolved, don't overwrite it.
             if (!string.IsNullOrEmpty(context.AccessToken))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
@@ -202,10 +202,10 @@ public static partial class OpenIddictValidationAspNetCoreHandlers
             {
                 context.AccessToken = header["Bearer ".Length..];
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -295,7 +295,7 @@ public static partial class OpenIddictValidationAspNetCoreHandlers
             // If a token was already resolved, don't overwrite it.
             if (!string.IsNullOrEmpty(context.AccessToken))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // This handler only applies to ASP.NET Core requests. If the HTTP context cannot be resolved,
@@ -309,10 +309,10 @@ public static partial class OpenIddictValidationAspNetCoreHandlers
             {
                 context.AccessToken = token;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -375,7 +375,7 @@ public static partial class OpenIddictValidationAspNetCoreHandlers
                 }
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -413,7 +413,7 @@ public static partial class OpenIddictValidationAspNetCoreHandlers
                 context.Response.Scope = properties.GetString(Properties.Scope);
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -463,7 +463,7 @@ public static partial class OpenIddictValidationAspNetCoreHandlers
                 _ => 400
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -502,7 +502,7 @@ public static partial class OpenIddictValidationAspNetCoreHandlers
             response.Headers[HeaderNames.Pragma] = "no-cache";
             response.Headers[HeaderNames.Expires] = "Thu, 01 Jan 1970 00:00:00 GMT";
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -545,7 +545,7 @@ public static partial class OpenIddictValidationAspNetCoreHandlers
 
             if (string.IsNullOrEmpty(context.Transaction.Response.Error))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Note: unlike the server stack, the validation stack doesn't expose any endpoint
@@ -606,7 +606,7 @@ public static partial class OpenIddictValidationAspNetCoreHandlers
 
             response.Headers.Append(HeaderNames.WWWAuthenticate, builder.ToString());
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -643,13 +643,13 @@ public static partial class OpenIddictValidationAspNetCoreHandlers
             // If the response doesn't contain a WWW-Authenticate header, don't return an empty response.
             if (!response.Headers.ContainsKey(HeaderNames.WWWAuthenticate))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             context.Logger.LogInformation(6141, SR.GetResourceString(SR.ID6141), context.Transaction.Response);
             context.HandleRequest();
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 }

src/OpenIddict.Validation.DataProtection/OpenIddictValidationDataProtectionHandlers.Protection.cs

@@ -10,7 +10,6 @@ using Microsoft.AspNetCore.DataProtection;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Microsoft.IdentityModel.Tokens;
-using OpenIddict.Extensions;
 using static OpenIddict.Validation.DataProtection.OpenIddictValidationDataProtectionConstants.Purposes;
 using static OpenIddict.Validation.OpenIddictValidationHandlers.Protection;
 using Schemes = OpenIddict.Validation.DataProtection.OpenIddictValidationDataProtectionConstants.Purposes.Schemes;
@@ -55,13 +54,13 @@ public static partial class OpenIddictValidationDataProtectionHandlers
                 // If a principal was already attached, don't overwrite it.
                 if (context.Principal is not null)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // If a specific token format is expected, return immediately if it doesn't match the expected value.
                 if (context.TokenFormat is not null and not TokenFormats.Private.DataProtection)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Note: ASP.NET Core Data Protection tokens created by the default implementation always start
@@ -78,7 +77,7 @@ public static partial class OpenIddictValidationDataProtectionHandlers
                         "Microsoft.AspNetCore.DataProtection.KeyManagement.KeyRingBasedDataProtectionProvider",
                         StringComparison.Ordinal))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Note: unlike the equivalent handler in the server stack, the logic used here is
@@ -101,14 +100,14 @@ public static partial class OpenIddictValidationDataProtectionHandlers
                         description: SR.GetResourceString(SR.ID2004),
                         uri: SR.FormatID8000(SR.ID2004));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 context.Principal = principal;
 
                 context.Logger.LogTrace(6152, SR.GetResourceString(SR.ID6152), context.Token, context.Principal.Claims);
 
-                return default;
+                return ValueTask.CompletedTask;
 
                 ClaimsPrincipal? ValidateToken(string type)
                 {

src/OpenIddict.Validation.Owin/OpenIddictValidationOwinHandlers.cs

@@ -12,7 +12,6 @@ using System.Text;
 using System.Text.Json;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
-using OpenIddict.Extensions;
 using Owin;
 using static OpenIddict.Validation.Owin.OpenIddictValidationOwinConstants;
 using Properties = OpenIddict.Validation.Owin.OpenIddictValidationOwinConstants.Properties;
@@ -105,7 +104,7 @@ public static partial class OpenIddictValidationOwinHandlers
             context.BaseUri = CreateUri(request.Scheme + Uri.SchemeDelimiter + host + request.PathBase);
             context.RequestUri = CreateUri(request.Scheme + Uri.SchemeDelimiter + host + request.PathBase + request.Path + request.QueryString);
 
-            return default;
+            return ValueTask.CompletedTask;
 
             // Note: the BCL System.Uri class has strict rules (e.g it rejects specific characters and enforces a
             // limit of 65519 characters for the complete URI representation). To ensure no exception is thrown if the
@@ -152,10 +151,10 @@ public static partial class OpenIddictValidationOwinHandlers
                     description: SR.FormatID2081(Headers.Host),
                     uri: SR.FormatID8000(SR.ID2081));
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -189,7 +188,7 @@ public static partial class OpenIddictValidationOwinHandlers
             // If a token was already resolved, don't overwrite it.
             if (!string.IsNullOrEmpty(context.AccessToken))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // This handler only applies to OWIN requests. If The OWIN request cannot be resolved,
@@ -204,10 +203,10 @@ public static partial class OpenIddictValidationOwinHandlers
             {
                 context.AccessToken = header["Bearer ".Length..];
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -298,7 +297,7 @@ public static partial class OpenIddictValidationOwinHandlers
             // If a token was already resolved, don't overwrite it.
             if (!string.IsNullOrEmpty(context.AccessToken))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // This handler only applies to OWIN requests. If The OWIN request cannot be resolved,
@@ -313,10 +312,10 @@ public static partial class OpenIddictValidationOwinHandlers
             {
                 context.AccessToken = token;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -349,7 +348,7 @@ public static partial class OpenIddictValidationOwinHandlers
             var properties = context.Transaction.GetProperty<AuthenticationProperties>(typeof(AuthenticationProperties).FullName!);
             if (properties is not { Dictionary.Count: > 0 })
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Note: unlike ASP.NET Core, OWIN's AuthenticationProperties doesn't offer a strongly-typed
@@ -395,7 +394,7 @@ public static partial class OpenIddictValidationOwinHandlers
                 }
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -433,7 +432,7 @@ public static partial class OpenIddictValidationOwinHandlers
                 context.Response.Scope = GetProperty(properties, Properties.Scope);
             }
 
-            return default;
+            return ValueTask.CompletedTask;
 
             static string? GetProperty(AuthenticationProperties properties, string name)
                 => properties.Dictionary.TryGetValue(name, out string? value) ? value : null;
@@ -486,7 +485,7 @@ public static partial class OpenIddictValidationOwinHandlers
                 _ => 400
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -539,7 +538,7 @@ public static partial class OpenIddictValidationOwinHandlers
                     properties         : response.Context.Authentication.AuthenticationResponseChallenge?.Properties ?? new());
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -584,7 +583,7 @@ public static partial class OpenIddictValidationOwinHandlers
                 TrySuppressFormsAuthenticationRedirect(response.Environment);
             }
 
-            return default;
+            return ValueTask.CompletedTask;
 
             static void TrySuppressFormsAuthenticationRedirect(IDictionary<string, object> environment)
             {
@@ -645,7 +644,7 @@ public static partial class OpenIddictValidationOwinHandlers
             response.Headers[Headers.Pragma] = "no-cache";
             response.Headers[Headers.Expires] = "Thu, 01 Jan 1970 00:00:00 GMT";
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -688,7 +687,7 @@ public static partial class OpenIddictValidationOwinHandlers
 
             if (string.IsNullOrEmpty(context.Transaction.Response.Error))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // Note: unlike the server stack, the validation stack doesn't expose any endpoint
@@ -749,7 +748,7 @@ public static partial class OpenIddictValidationOwinHandlers
 
             response.Headers.Append(Headers.WwwAuthenticate, builder.ToString());
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -786,13 +785,13 @@ public static partial class OpenIddictValidationOwinHandlers
             // If the response doesn't contain a WWW-Authenticate header, don't return an empty response.
             if (!response.Headers.ContainsKey(Headers.WwwAuthenticate))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             context.Logger.LogInformation(6141, SR.GetResourceString(SR.ID6141), context.Transaction.Response);
             context.HandleRequest();
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 }

src/OpenIddict.Validation.SystemNetHttp/OpenIddictValidationSystemNetHttpHandlers.cs

@@ -16,7 +16,6 @@ using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Microsoft.Extensions.Primitives;
 using Microsoft.IdentityModel.Tokens;
-using OpenIddict.Extensions;
 using static OpenIddict.Validation.SystemNetHttp.OpenIddictValidationSystemNetHttpConstants;
 
 namespace OpenIddict.Validation.SystemNetHttp;
@@ -68,7 +67,7 @@ public static partial class OpenIddictValidationSystemNetHttpHandlers
             // If an explicit client authentication method was attached, don't overwrite it.
             if (!string.IsNullOrEmpty(context.IntrospectionEndpointClientAuthenticationMethod))
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             context.IntrospectionEndpointClientAuthenticationMethod = (
@@ -147,7 +146,7 @@ public static partial class OpenIddictValidationSystemNetHttpHandlers
                 _ => null
             };
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -217,7 +216,7 @@ public static partial class OpenIddictValidationSystemNetHttpHandlers
             context.Transaction.SetProperty(typeof(HttpClient).FullName!, _factory.CreateClient(builder.ToString()) ??
                 throw new InvalidOperationException(SR.GetResourceString(SR.ID0174)));
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -249,7 +248,7 @@ public static partial class OpenIddictValidationSystemNetHttpHandlers
             context.Transaction.SetProperty(typeof(HttpRequestMessage).FullName!,
                 new HttpRequestMessage(HttpMethod.Get, context.RemoteUri));
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -281,7 +280,7 @@ public static partial class OpenIddictValidationSystemNetHttpHandlers
             context.Transaction.SetProperty(typeof(HttpRequestMessage).FullName!,
                 new HttpRequestMessage(HttpMethod.Post, context.RemoteUri));
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -328,7 +327,7 @@ public static partial class OpenIddictValidationSystemNetHttpHandlers
             request.VersionPolicy = client.DefaultVersionPolicy;
 #endif
 #endif
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -369,7 +368,7 @@ public static partial class OpenIddictValidationSystemNetHttpHandlers
             // that require using HTTP compression can register a custom event handler to send an
             // Accept-Encoding header containing the supported algorithms (e.g GZip/Deflate/Brotli).
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -425,7 +424,7 @@ public static partial class OpenIddictValidationSystemNetHttpHandlers
                 productName: assembly.Name!,
                 productVersion: assembly.Version!.ToString()));
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -466,7 +465,7 @@ public static partial class OpenIddictValidationSystemNetHttpHandlers
             // Attach the contact address specified in the options, if available.
             request.Headers.From = _options.CurrentValue.ContactAddress?.ToString();
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -520,7 +519,7 @@ public static partial class OpenIddictValidationSystemNetHttpHandlers
                 context.Transaction.Request.ClientId = context.Transaction.Request.ClientSecret = null;
             }
 
-            return default;
+            return ValueTask.CompletedTask;
 
             static string? EscapeDataString(string? value)
                 => value is not null ? Uri.EscapeDataString(value).Replace("%20", "+") : null;
@@ -560,7 +559,7 @@ public static partial class OpenIddictValidationSystemNetHttpHandlers
 
             if (context.Transaction.Request.Count is 0)
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // For GET requests, attach the request parameters to the query string by default.
@@ -583,7 +582,7 @@ public static partial class OpenIddictValidationSystemNetHttpHandlers
                     select new KeyValuePair<string?, string?>(parameter.Key, value));
             }
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -685,7 +684,7 @@ public static partial class OpenIddictValidationSystemNetHttpHandlers
             // Remove the request from the transaction properties.
             context.Transaction.SetProperty<HttpRequestMessage>(typeof(HttpRequestMessage).FullName!, null);
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 
@@ -941,7 +940,7 @@ public static partial class OpenIddictValidationSystemNetHttpHandlers
             // Don't overwrite the response if one was already provided.
             if (context.Transaction.Response is not null)
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             // This handler only applies to System.Net.Http requests. If the HTTP response cannot be resolved,
@@ -951,14 +950,14 @@ public static partial class OpenIddictValidationSystemNetHttpHandlers
 
             if (response.Headers.WwwAuthenticate.Count is 0)
             {
-                return default;
+                return ValueTask.CompletedTask;
             }
 
             context.Transaction.Response = new OpenIddictResponse(response.Headers.WwwAuthenticate
                 .Where(static header => !string.IsNullOrEmpty(header.Parameter))
                 .SelectMany(static header => ParseParameters(header.Parameter!)));
 
-            return default;
+            return ValueTask.CompletedTask;
 
             static IEnumerable<KeyValuePair<string, string?>> ParseParameters(string parameter)
             {
@@ -1147,7 +1146,7 @@ public static partial class OpenIddictValidationSystemNetHttpHandlers
             // Remove the response from the transaction properties.
             context.Transaction.SetProperty<HttpResponseMessage>(typeof(HttpResponseMessage).FullName!, null);
 
-            return default;
+            return ValueTask.CompletedTask;
         }
     }
 }

src/OpenIddict.Validation/OpenIddictValidationBuilder.cs

@@ -12,7 +12,6 @@ using System.Security.Claims;
 using System.Security.Cryptography.X509Certificates;
 using Microsoft.Extensions.DependencyInjection.Extensions;
 using Microsoft.IdentityModel.Tokens;
-using OpenIddict.Extensions;
 using OpenIddict.Validation;
 
 namespace Microsoft.Extensions.DependencyInjection;

src/OpenIddict.Validation/OpenIddictValidationConfiguration.cs

@@ -8,7 +8,6 @@ using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Options;
 using Microsoft.IdentityModel.Protocols;
 using Microsoft.IdentityModel.Tokens;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Validation;
 

src/OpenIddict.Validation/OpenIddictValidationDispatcher.cs

@@ -7,7 +7,6 @@
 using System.ComponentModel;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Validation;
 

src/OpenIddict.Validation/OpenIddictValidationHandlers.Discovery.cs

@@ -8,7 +8,6 @@ using System.Collections.Immutable;
 using System.Text.Json;
 using Microsoft.Extensions.Logging;
 using Microsoft.IdentityModel.Tokens;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Validation;
 
@@ -69,11 +68,11 @@ public static partial class OpenIddictValidationHandlers
                             description: SR.FormatID2107(parameter.Key),
                             uri: SR.FormatID8000(SR.ID2107));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
 
                 // Note: in the typical case, the response parameters should be deserialized from a
                 // JSON response and thus natively stored as System.Text.Json.JsonElement instances.
@@ -147,10 +146,10 @@ public static partial class OpenIddictValidationHandlers
                         description: SR.GetResourceString(SR.ID2144),
                         uri: SR.FormatID8000(SR.ID2144));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -188,7 +187,7 @@ public static partial class OpenIddictValidationHandlers
                         description: SR.GetResourceString(SR.ID2096),
                         uri: SR.FormatID8000(SR.ID2096));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 if (!Uri.TryCreate(issuer, UriKind.Absolute, out Uri? uri))
@@ -198,7 +197,7 @@ public static partial class OpenIddictValidationHandlers
                         description: SR.GetResourceString(SR.ID2097),
                         uri: SR.FormatID8000(SR.ID2097));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Ensure the issuer matches the expected value.
@@ -209,12 +208,12 @@ public static partial class OpenIddictValidationHandlers
                         description: SR.GetResourceString(SR.ID2098),
                         uri: SR.FormatID8000(SR.ID2098));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 context.Configuration.Issuer = uri;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -251,7 +250,7 @@ public static partial class OpenIddictValidationHandlers
                         description: SR.GetResourceString(SR.ID2099),
                         uri: SR.FormatID8000(SR.ID2099));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 if (!Uri.TryCreate(endpoint, UriKind.Absolute, out Uri? uri) || OpenIddictHelpers.IsImplicitFileUri(uri))
@@ -261,12 +260,12 @@ public static partial class OpenIddictValidationHandlers
                         description: SR.FormatID2100(Metadata.JwksUri),
                         uri: SR.FormatID8000(SR.ID2100));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 context.Configuration.JsonWebKeySetUri = uri;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -303,13 +302,13 @@ public static partial class OpenIddictValidationHandlers
                             description: SR.FormatID2100(Metadata.IntrospectionEndpoint),
                             uri: SR.FormatID8000(SR.ID2100));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
 
                     context.Configuration.IntrospectionEndpoint = uri;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -345,7 +344,7 @@ public static partial class OpenIddictValidationHandlers
                     context.Configuration.MtlsIntrospectionEndpoint = uri;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -382,7 +381,7 @@ public static partial class OpenIddictValidationHandlers
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -418,11 +417,11 @@ public static partial class OpenIddictValidationHandlers
                             description: SR.FormatID2107(parameter.Key),
                             uri: SR.FormatID8000(SR.ID2107));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
 
                 // Note: in the typical case, the response parameters should be deserialized from a
                 // JSON response and thus natively stored as System.Text.Json.JsonElement instances.
@@ -484,10 +483,10 @@ public static partial class OpenIddictValidationHandlers
                         description: SR.GetResourceString(SR.ID2145),
                         uri: SR.FormatID8000(SR.ID2145));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -522,7 +521,7 @@ public static partial class OpenIddictValidationHandlers
                         description: SR.FormatID2102(JsonWebKeySetParameterNames.Keys),
                         uri: SR.FormatID8000(SR.ID2102));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 for (var index = 0; index < keys.Count; index++)
@@ -573,7 +572,7 @@ public static partial class OpenIddictValidationHandlers
                             description: SR.GetResourceString(SR.ID2103),
                             uri: SR.FormatID8000(SR.ID2103));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
 
                     // If the key is a RSA key, ensure the mandatory parameters are all present.
@@ -585,7 +584,7 @@ public static partial class OpenIddictValidationHandlers
                             description: SR.GetResourceString(SR.ID2104),
                             uri: SR.FormatID8000(SR.ID2104));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
 
                     // If the key is an EC key, ensure the mandatory parameters are all present.
@@ -597,7 +596,7 @@ public static partial class OpenIddictValidationHandlers
                             description: SR.GetResourceString(SR.ID2104),
                             uri: SR.FormatID8000(SR.ID2104));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
 
                     key.KeyId = (string?) keys[index][JsonWebKeyParameterNames.Kid];
@@ -620,7 +619,7 @@ public static partial class OpenIddictValidationHandlers
                     context.SecurityKeys.Keys.Add(key);
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Validation/OpenIddictValidationHandlers.Introspection.cs

@@ -10,7 +10,6 @@ using System.Globalization;
 using System.Security.Claims;
 using System.Text.Json;
 using Microsoft.Extensions.Logging;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Validation;
 
@@ -65,11 +64,11 @@ public static partial class OpenIddictValidationHandlers
                             description: SR.FormatID2107(parameter.Key),
                             uri: SR.FormatID8000(SR.ID2107));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
 
                 // Note: in the typical case, the response parameters should be deserialized from a
                 // JSON response and thus natively stored as System.Text.Json.JsonElement instances.
@@ -149,10 +148,10 @@ public static partial class OpenIddictValidationHandlers
                         description: SR.GetResourceString(SR.ID2146),
                         uri: SR.FormatID8000(SR.ID2146));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -192,7 +191,7 @@ public static partial class OpenIddictValidationHandlers
                         description: SR.FormatID2105(Parameters.Active),
                         uri: SR.FormatID8000(SR.ID2105));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 if (active is not true)
@@ -202,10 +201,10 @@ public static partial class OpenIddictValidationHandlers
                         description: SR.GetResourceString(SR.ID2106),
                         uri: SR.FormatID8000(SR.ID2106));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -244,7 +243,7 @@ public static partial class OpenIddictValidationHandlers
                             description: SR.GetResourceString(SR.ID2108),
                             uri: SR.FormatID8000(SR.ID2108));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
 
                     // Ensure the issuer matches the expected value.
@@ -255,11 +254,11 @@ public static partial class OpenIddictValidationHandlers
                             description: SR.GetResourceString(SR.ID2109),
                             uri: SR.FormatID8000(SR.ID2109));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -303,10 +302,10 @@ public static partial class OpenIddictValidationHandlers
                         description: SR.GetResourceString(SR.ID2176),
                         uri: SR.FormatID8000(SR.ID2176));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -341,7 +340,7 @@ public static partial class OpenIddictValidationHandlers
                 // whether the returned token has an acceptable type depending on the context.
                 switch ((string?) context.Response[Claims.TokenUsage])
                 {
-                    case null or { Length: 0 }: return default;
+                    case null or { Length: 0 }: return ValueTask.CompletedTask;
 
                     // Note: by default, OpenIddict only allows access/refresh tokens to be
                     // introspected but additional types can be added using the events model.
@@ -359,10 +358,10 @@ public static partial class OpenIddictValidationHandlers
                             description: SR.GetResourceString(SR.ID2118),
                             uri: SR.FormatID8000(SR.ID2118));
 
-                        return default;
+                        return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -445,7 +444,7 @@ public static partial class OpenIddictValidationHandlers
 
                 context.Principal = new ClaimsPrincipal(identity);
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -511,7 +510,7 @@ public static partial class OpenIddictValidationHandlers
                     _ => []
                 });
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }

src/OpenIddict.Validation/OpenIddictValidationHandlers.Protection.cs

@@ -10,7 +10,6 @@ using System.Globalization;
 using System.Security.Claims;
 using Microsoft.Extensions.Logging;
 using Microsoft.IdentityModel.Tokens;
-using OpenIddict.Extensions;
 
 namespace OpenIddict.Validation;
 
@@ -133,7 +132,7 @@ public static partial class OpenIddictValidationHandlers
                 context.SecurityTokenHandler = context.Options.JsonWebTokenHandler;
                 context.TokenValidationParameters = parameters;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -163,7 +162,7 @@ public static partial class OpenIddictValidationHandlers
                 // If no character was explicitly added, all characters are considered valid.
                 if (context.AllowedCharset.Count is 0)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Remove the disallowed characters from the token string. If the token is
@@ -176,12 +175,12 @@ public static partial class OpenIddictValidationHandlers
                         description: SR.GetResourceString(SR.ID2004),
                         uri: SR.FormatID8000(SR.ID2004));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 context.Token = token;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -403,7 +402,7 @@ public static partial class OpenIddictValidationHandlers
 
                 if (context.Principal is null)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // Note: in previous OpenIddict versions, scopes were represented as a JSON array
@@ -419,7 +418,7 @@ public static partial class OpenIddictValidationHandlers
                     context.Principal.SetClaim(Claims.Scope, string.Join(" ", scopes));
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -448,7 +447,7 @@ public static partial class OpenIddictValidationHandlers
 
                 if (context.Principal is null)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // To reduce the size of tokens, some of the private claims used by OpenIddict
@@ -522,7 +521,7 @@ public static partial class OpenIddictValidationHandlers
                     }
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -625,7 +624,7 @@ public static partial class OpenIddictValidationHandlers
                         description: SR.GetResourceString(SR.ID2004),
                         uri: SR.FormatID8000(SR.ID2004));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // When using JWT or Data Protection tokens, the correct token type is always enforced by IdentityModel
@@ -643,7 +642,7 @@ public static partial class OpenIddictValidationHandlers
                     throw new InvalidOperationException(SR.FormatID0005(type, string.Join(", ", context.ValidTokenTypes)));
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -683,10 +682,10 @@ public static partial class OpenIddictValidationHandlers
                         description: SR.GetResourceString(SR.ID2019),
                         uri: SR.FormatID8000(SR.ID2019));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -719,7 +718,7 @@ public static partial class OpenIddictValidationHandlers
                 // If no specific value is expected, skip the default presenter validation.
                 if (context.ValidPresenters.Count is 0)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // If the token doesn't have any presenter attached, return an error.
@@ -733,7 +732,7 @@ public static partial class OpenIddictValidationHandlers
                         description: SR.GetResourceString(SR.ID2184),
                         uri: SR.FormatID8000(SR.ID2184));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // If the token doesn't include any registered presenter, return an error.
@@ -746,10 +745,10 @@ public static partial class OpenIddictValidationHandlers
                         description: SR.GetResourceString(SR.ID2185),
                         uri: SR.FormatID8000(SR.ID2185));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -782,7 +781,7 @@ public static partial class OpenIddictValidationHandlers
                 // If no specific value is expected, skip the default audience validation.
                 if (context.ValidAudiences.Count is 0)
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // If the token doesn't have any audience attached, return an error.
@@ -796,7 +795,7 @@ public static partial class OpenIddictValidationHandlers
                         description: SR.GetResourceString(SR.ID2093),
                         uri: SR.FormatID8000(SR.ID2093));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 // If the token doesn't include any registered audience, return an error.
@@ -809,10 +808,10 @@ public static partial class OpenIddictValidationHandlers
                         description: SR.GetResourceString(SR.ID2094),
                         uri: SR.FormatID8000(SR.ID2094));
 
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -946,7 +945,7 @@ public static partial class OpenIddictValidationHandlers
                 context.SecurityTokenDescriptor.SigningCredentials = context.Options.SigningCredentials.First();
                 context.SecurityTokenHandler = context.Options.JsonWebTokenHandler;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -993,7 +992,7 @@ public static partial class OpenIddictValidationHandlers
 
                 context.SecurityTokenDescriptor.Subject = (ClaimsIdentity) principal.Identity;
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1056,7 +1055,7 @@ public static partial class OpenIddictValidationHandlers
                     string value => value
                 };
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
 
@@ -1087,7 +1086,7 @@ public static partial class OpenIddictValidationHandlers
                 // If a token was already attached by another handler, don't overwrite it.
                 if (!string.IsNullOrEmpty(context.Token))
                 {
-                    return default;
+                    return ValueTask.CompletedTask;
                 }
 
                 context.Token = context.SecurityTokenHandler.CreateToken(context.SecurityTokenDescriptor);
@@ -1095,7 +1094,7 @@ public static partial class OpenIddictValidationHandlers
                 context.Logger.LogTrace(6013, SR.GetResourceString(SR.ID6013), context.TokenType,
                     context.Token, context.SecurityTokenDescriptor.Subject?.Claims ?? []);
 
-                return default;
+                return ValueTask.CompletedTask;
             }
         }
     }