protected function getRelativeHandlerClassNamePieces($handler_type_key, $handler_type_info) {
    $handler_short_class_name = $this->makeShortHandlerClassName($handler_type_key, $handler_type_info);
    if (isset($handler_type_info['class_namespace'])) {
      $handler_relative_class_name = $handler_type_info['class_namespace'];
      $handler_relative_class_name[] = $handler_short_class_name;
    }
    else {
      $handler_relative_class_name = [
        'Entity',
        'Handler',
        $handler_short_class_name,
      ];
    }

    return $handler_relative_class_name;
  }