code: protected function defaultSort()
      {
          return collect($this->defaultSort)->map(function ($param) {
              $desc = ($param[0] === '-');
              $field = ltrim($param, '-');
  
              return new SortParameter($field, !$desc);
          })->all();
      }
docs: Get sort parameters to use when the client has not provided a sort order.
  
  @return array