public function index()
    {
        // if the test taker passes by this page, he/she cannot access to any delivery without proctor authorization,
        // whatever the delivery execution status is.
        $user = common_session_SessionManager::getSession()->getUser();
        $startedExecutions = $this->service->getResumableDeliveries($user);
        foreach($startedExecutions as $startedExecution) {
            if($startedExecution->getDelivery()->exists()) {
                $this->revoke($startedExecution);
            }
        }

        parent::index();
    }