code: def undeclared_query_parameters(self):
          
          parameters = []
          undeclared = self._job_statistics().get("undeclaredQueryParameters", ())
  
          for parameter in undeclared:
              p_type = parameter["parameterType"]
  
              if "arrayType" in p_type:
                  klass = ArrayQueryParameter
              elif "structTypes" in p_type:
                  klass = StructQueryParameter
              else:
                  klass = ScalarQueryParameter
  
              parameters.append(klass.from_api_repr(parameter))
  
          return parameters
docs: Return undeclared query parameters from job statistics, if present.
  
          See:
          https://cloud.google.com/bigquery/docs/reference/rest/v2/jobs#statistics.query.undeclaredQueryParameters
  
          :rtype:
              list of
              :class:`~google.cloud.bigquery.ArrayQueryParameter`,
              :class:`~google.cloud.bigquery.ScalarQueryParameter`, or
              :class:`~google.cloud.bigquery.StructQueryParameter`
          :returns: undeclared parameters, or an empty list if the query has
                    not yet completed.