udaf with user defined pojo object throw error while generate record equaliser

Udaf with user define pojo object throw error while generating record equaliser: 

When user create an udaf while recore contains user define complex pojo object (like List<UserDefinedObject> or Map<UserDefinedObject>). The codegen will throw error while generating record equaliser, the error is:

A method named "compareTo" is not declared in any enclosing class nor any subtype, nor through a static import.