Support more IAsyncEnumerable types in SignalR (#24926)

Author: BrennanConroy

src/SignalR/common/Shared/ReflectionHelper.cs

@@ -1,5 +1,5 @@
 // Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information. 
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 #nullable disable
 
@@ -39,7 +39,10 @@ public static bool IsIAsyncEnumerable(Type type)
         {
             if (type.IsGenericType)
             {
-                return type.GetGenericTypeDefinition() == typeof(IAsyncEnumerable<>);
+                if (type.GetGenericTypeDefinition() == typeof(IAsyncEnumerable<>))
+                {
+                    return true;
+                }
             }
 
             return type.GetInterfaces().Any(t =>

src/SignalR/server/SignalR/test/Internal/ReflectionHelperTests.cs

@@ -57,6 +57,12 @@ async IAsyncEnumerable<int> Stream()
                 typeof(CustomAsyncEnumerable),
                 true
             };
+
+            yield return new object[]
+            {
+                typeof(CustomAsyncEnumerableOfT<object>),
+                true
+            };
         }
 
         private class CustomAsyncEnumerable : IAsyncEnumerable<object>
@@ -66,5 +72,13 @@ public IAsyncEnumerator<object> GetAsyncEnumerator(CancellationToken cancellatio
                 throw new NotImplementedException();
             }
         }
+
+        private class CustomAsyncEnumerableOfT<T> : IAsyncEnumerable<object>
+        {
+            public IAsyncEnumerator<object> GetAsyncEnumerator(CancellationToken cancellationToken = default)
+            {
+                throw new NotImplementedException();
+            }
+        }
     }
 }