code: protected function verifyRequiredData()
      {
          $errors = array();
          foreach ($this->_REQUIRED_DATA as $property => $defaultValue) {
              if ((!isset($this->Data[$property])) && empty($defaultValue)) {
                  $errors[] = $property;
              }
          }
          if (count($errors) > 0) {
              throw new RequiredDataException(get_called_class(), "Missing data for ".implode(",", $errors));
          }
          return true;
      }
docs: Validate Required Data for the Endpoint
  @return bool
  @throws RequiredDataException