code: public function getRouteCollectionForRequest(Request $request): RouteCollection
      {
          $this->framework->initialize(true);
  
          $pathInfo = rawurldecode($request->getPathInfo());
  
          // The request string must not contain "auto_item" (see #4012)
          if (false !== strpos($pathInfo, '/auto_item/')) {
              return new RouteCollection();
          }
  
          $routes = [];
  
          if ('/' === $pathInfo || ($this->prependLocale && preg_match('@^/([a-z]{2}(-[A-Z]{2})?)/$@', $pathInfo))) {
              $this->addRoutesForRootPages($this->findRootPages($request->getHttpHost()), $routes);
  
              return $this->createCollectionForRoutes($routes, $request->getLanguages());
          }
  
          $pathInfo = $this->removeSuffixAndLanguage($pathInfo);
  
          if (null === $pathInfo) {
              return new RouteCollection();
          }
  
          $candidates = $this->getAliasCandidates($pathInfo);
          $pages = $this->findPages($candidates);
  
          $this->addRoutesForPages($pages, $routes);
  
          return $this->createCollectionForRoutes($routes, $request->getLanguages());
      }
docs: {@inheritdoc}