code: public function onKernelRequest(GetResponseEvent $event)
      {
          $token = $this->securityContext->getToken();
          if (null === $token) {
              return;
          }
  
          $username = null;
          if ( ! $this->configurationHandler->isTheme()) {
              $username = $token->getUser()->getUsername();
          }
          
          $this->pagesCollectionParser
              ->contributor($username)
              ->parse()
          ;
  
          $this->themeGenerator->generate();
          $this->slotsGenerator->synchronize($this->page, $this->pagesCollectionParser->pages());
          $this->themeAligner->align($this->pagesCollectionParser);
          $this->slotsGenerator->generate();
      }
docs: Aligns the site slots
  
  @param GetResponseEvent $event