Inheritance: extends Exception
 protected function validateSession($session)
 {
     try {
         if (is_null($this->shareToken)) {
             new File($session->getFileId());
         } else {
             File::getByShareToken($this->shareToken);
         }
     } catch (\Exception $e) {
         $this->logger->warning('Error. Session no longer exists. ' . $e->getMessage(), ['app' => $this->appName]);
         $ex = new BadRequestException();
         $ex->setBody(implode(',', $this->request->getParams()));
         throw $ex;
     }
 }