.NET: Added support for polymorphic type as workflow output (#4485)

* Added support for polymorphic type as workflow output

* Update Linq expression to avoid unnecessary allocations.

* Added caching as per PR comment

dotnet/src/Microsoft.Agents.AI.Workflows/Executor.cs

@@ -3,6 +3,7 @@
 #pragma warning disable CS0618 // Type or member is obsolete - Internal use of obsolete types for backward compatibility
 
 using System;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
@@ -133,7 +134,25 @@ internal sealed class ExecutorProtocol(MessageRouter router, ISet<Type> sendType
 
     public bool CanHandle(Type type) => router.CanHandle(type);
 
-    public bool CanOutput(Type type) => this._yieldTypes.Contains(new(type));
+    private readonly ConcurrentDictionary<Type, bool> _canOutputCache = new();
+
+    public bool CanOutput(Type type)
+    {
+        return this._canOutputCache.GetOrAdd(type, this.CanOutputCore);
+    }
+
+    private bool CanOutputCore(Type type)
+    {
+        foreach (TypeId yieldType in this._yieldTypes)
+        {
+            if (yieldType.IsMatchPolymorphic(type))
+            {
+                return true;
+            }
+        }
+
+        return false;
+    }
 
     public ProtocolDescriptor Describe() => new(this.Router.IncomingTypes, yieldTypes, sendTypes, this.Router.HasCatchAll);
 }