Bring back original TransferDataSource API and mark it obsolete.

Xwt/Xwt/TransferDataSource.cs

@@ -157,8 +157,30 @@ public static byte[] SerializeValue (object val, Type type)
 		public static object DeserializeValue (byte[] data, Type type)
 		{
 			return JsonSerializer.Deserialize (data, type);
-		}
-	}
+        }
+
+        /// <summary>
+        /// Serializes a value to a byte array using <see cref="System.Runtime.Serialization.Formatters.Binary.BinaryFormatter"/> .
+        /// </summary>
+        /// <returns>The serialized value.</returns>
+        /// <param name="val">The value to serialize.</param>
+		[Obsolete("Use SerializeValue (object val, Type type) instead", true)]
+        public static byte[] SerializeValue(object val)
+        {
+			return new byte[0];
+        }
+
+        /// <summary>
+        /// Deserializes a value from a byte array.
+        /// </summary>
+        /// <returns>The deserialized value.</returns>
+        /// <param name="data">The byte array containing the serialized value.</param>
+		[Obsolete("Use DeserializeValue (byte[] data, Type type) instead", true)]
+        public static object DeserializeValue(byte[] data)
+        {
+			return null;
+        }
+    }
 
 	/// <summary>
 	/// Data request delegate, returns the data for a specific transfer data type request.