code: def _DecodeUnknownMessages(message, encoded_message, pair_type):
      
      field_type = pair_type.value.type
      new_values = []
      all_field_names = [x.name for x in message.all_fields()]
      for name, value_dict in six.iteritems(encoded_message):
          if name in all_field_names:
              continue
          value = PyValueToMessage(field_type, value_dict)
          if pair_type.value.repeated:
              value = _AsMessageList(value)
          new_pair = pair_type(key=name, value=value)
          new_values.append(new_pair)
      return new_values
docs: Process unknown fields in encoded_message of a message type.