Backport fix on IAsyncEnumerable from 5.0 to 3.1 (https://github.com/dotnet/aspnetcore/pull/24926/files) (#25177)

Author: tebeco

src/SignalR/common/Shared/ReflectionHelper.cs

@@ -37,7 +37,10 @@ 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();
+            }
+        }
     }
 }