code: public function redirectToLogin($query = null, $httpRequest = null)
      {
          /* Attempt to extract afterLogin param from the request referer.
           * Login form submissions are sent to /login (without any GET query params)
           * So in case of unsuccessful login attempt the afterLogin information would be lost.
           */
          if ($httpRequest && $httpRequest->headers->has("referer")) {
              $referer = $httpRequest->headers->get("referer");
              $page = Utils::getRefererQueryParam($referer, "afterLogin");
              if (Utils::isValidPageId($page)) {
                  $query .= ($query ? '&' : '') . "afterLogin=" . $page;
              }
          }
  
          $this->redirectToPage("login", $query);
      }
docs: {@inheritdoc}