Set the page online if called from a certain path.
\Symfony\Component\HttpKernel\Event\GetResponseEvent $event: The event to process.
public function onKernelRequestMaintenance(GetResponseEvent $event) {
$request = $event
->getRequest();
// Allow access to menu_login_callback even if in maintenance mode.
if ($request->attributes
->get('_maintenance') == MENU_SITE_OFFLINE && $request->attributes
->get('system_path') == 'menu_login_callback') {
$request->attributes
->set('_maintenance', MENU_SITE_ONLINE);
}
}