Contao\CoreBundle\Framework\ContaoFrameworkInterface::isInitialized PHP Method

    public function isInitialized();

 /**
  * Adds the Contao headers to the Symfony response.
  *
  * @param FilterResponseEvent $event The event object
  */
 public function onKernelResponse(FilterResponseEvent $event)
 {
     if (!$this->contaoFramework->isInitialized()) {
         return;
     }
     $event->setResponse($this->mergeHttpHeaders($event->getResponse()));
 }