Introduce OpenIddictMessage.Count to allow retrieving the number of parameters contained in a message

src/OpenIddict.Abstractions/Primitives/OpenIddictMessage.cs

@@ -174,6 +174,11 @@ namespace OpenIddict.Abstractions
             set => SetParameter(name, value);
         }
 
+        /// <summary>
+        /// Gets the number of parameters contained in the current message.
+        /// </summary>
+        public int Count => Parameters.Count;
+
         /// <summary>
         /// Gets the dictionary containing the parameters.
         /// </summary>

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

@@ -200,7 +200,7 @@ namespace OpenIddict.Server.AspNetCore
                     // Don't cache the request if the request doesn't include any parameter.
                     // If a request_id parameter can be found in the authorization request,
                     // ignore the following logic to prevent an infinite redirect loop.
-                    if (context.Request.GetParameters().IsEmpty || !string.IsNullOrEmpty(context.Request.RequestId))
+                    if (context.Request.Count == 0 || !string.IsNullOrEmpty(context.Request.RequestId))
                     {
                         return;
                     }

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

@@ -198,7 +198,7 @@ namespace OpenIddict.Server.AspNetCore
                     // Don't cache the request if the request doesn't include any parameter.
                     // If a request_id parameter can be found in the logout request,
                     // ignore the following logic to prevent an infinite redirect loop.
-                    if (context.Request.GetParameters().IsEmpty || !string.IsNullOrEmpty(context.Request.RequestId))
+                    if (context.Request.Count == 0 || !string.IsNullOrEmpty(context.Request.RequestId))
                     {
                         return;
                     }

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

@@ -197,7 +197,7 @@ namespace OpenIddict.Server.Owin
                     // Don't cache the request if the request doesn't include any parameter.
                     // If a request_id parameter can be found in the authorization request,
                     // ignore the following logic to prevent an infinite redirect loop.
-                    if (context.Request.GetParameters().IsEmpty || !string.IsNullOrEmpty(context.Request.RequestId))
+                    if (context.Request.Count == 0 || !string.IsNullOrEmpty(context.Request.RequestId))
                     {
                         return;
                     }

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

@@ -195,7 +195,7 @@ namespace OpenIddict.Server.Owin
                     // Don't cache the request if the request doesn't include any parameter.
                     // If a request_id parameter can be found in the logout request,
                     // ignore the following logic to prevent an infinite redirect loop.
-                    if (context.Request.GetParameters().IsEmpty || !string.IsNullOrEmpty(context.Request.RequestId))
+                    if (context.Request.Count == 0 || !string.IsNullOrEmpty(context.Request.RequestId))
                     {
                         return;
                     }