Fix serialization of ControlReference when used in prefabs

#3262

Source/Engine/Serialization/JsonSerializer.cs

@@ -228,6 +228,23 @@ namespace FlaxEngine.Json
             CacheManagedOnly.Dispose();
         }
 
+        /// <summary>
+        /// The default implementation of the values comparision function used by the serialization system.
+        /// </summary>
+        /// <param name="objA">The object a.</param>
+        /// <param name="objB">The object b.</param>
+        /// <returns>True if both objects are equal, otherwise false.</returns>
+        public static bool SceneObjectEquals(SceneObject objA, SceneObject objB)
+        {
+            if (objA == objB)
+                return true;
+            if (objA == null || objB == null)
+                return false;
+            if (objA.HasPrefabLink && objB.HasPrefabLink)
+                return objA.PrefabObjectID == objB.PrefabObjectID;
+            return false;
+        }
+
         /// <summary>
         /// The default implementation of the values comparision function used by the serialization system.
         /// </summary>