private function checkPermission(Event $event)
 {
     if ($event->isEditable() === false) {
         throw new AccessDeniedException('You cannot edit this event');
     }
     if ($event->getWorkspace()) {
         if (!$this->authorization->isGranted(array('agenda_', 'edit'), $event->getWorkspace())) {
             throw new AccessDeniedException('You cannot edit the agenda');
         }
         return;
     }
     if ($this->tokenStorage->getToken()->getUser() != $event->getUser()) {
         throw new AccessDeniedException('You cannot edit the agenda');
     }
 }