/**
  * @copydoc CategoryGridHandler::getCategoryRowInstance()
  * @return CopyeditingFilesGridCategoryRow
  */
 protected function getCategoryRowInstance()
 {
     $row = new SignoffFilesGridCategoryRow($this->getStageId());
     $submission = $this->getSubmission();
     $row->setCellProvider(new SignoffFilesGridCellProvider($submission->getId(), $this->getStageId()));
     $row->addFlag('gridRowStyle', true);
     return $row;
 }