docs: def payload(self):
      """The payload property automatically decodes the encapsulated data."""
      if self.args_rdf_name:
        # Now try to create the correct RDFValue.
        result_cls = self.classes.get(self.args_rdf_name, rdfvalue.RDFString)
  
        result = result_cls.FromSerializedString(
            self.Get("args"), age=self.args_age)
        return result