private function createResponse(ProgressBar $progressbar)
 {
     $nextProgressbar = null;
     if ($progressbar->isFinished() || $progressbar->isCancelled()) {
         $this->progressbarManager->remove($progressbar->getToken());
         if ($progressbar instanceof StackProgressBar && $progressbar->getNextProgressbarToken()) {
             $nextProgressbar = $this->progressbarManager->load($progressbar->getNextProgressbarToken());
         }
     } else {
         $this->progressbarManager->save($progressbar);
     }
     return $progressbar->getJsonResponse($nextProgressbar);
 }