code: public static void makeMethodBodyEmpty(MethodGen mg) {
  
      mg.setInstructionList(new InstructionList(new RETURN()));
      mg.removeExceptionHandlers();
      mg.removeLineNumbers();
      mg.removeLocalVariables();
      mg.setMaxLocals();
    }
docs: Empties the method of all code (except for a return). This includes line numbers, exceptions,
  local variables, etc.
  
  @param mg the method to clear out