obsoleting legacy prop eds

src/umbraco.editorControls/MultiNodeTreePicker/MNTP_PrevalueEditor.cs

@@ -14,6 +14,7 @@ namespace umbraco.editorControls.MultiNodeTreePicker
     /// <summary>
     /// The pre-value editor for the multi node tree picker.
     /// </summary>
+    [Obsolete("IDataType and all other references to the legacy property editors are no longer used this will be removed from the codebase in future versions")]
     public class MNTP_PrevalueEditor : Control, IDataPrevalue
     {
         private readonly umbraco.cms.businesslogic.datatype.BaseDataType m_DataType;