class RouteProcessor

class RouteProcessor implements OutboundRouteProcessorInterface {
    
    /**
     * The route provider.
     *
     * @var \Drupal\Core\Routing\RouteProviderInterface
     */
    protected $routeProvider;
    
    /**
     * Constructs a RouteProcessor object.
     *
     * @param \Drupal\Core\Routing\RouteProviderInterface $route_provider
     *   The route provider.
     */
    public function __construct(RouteProviderInterface $route_provider) {
        $this->routeProvider = $route_provider;
    }
    
    /**
     * {@inheritdoc}
     */
    public function processOutbound($route_name, Route $route, array &$parameters, BubbleableMetadata $bubbleable_metadata = NULL) {
        $redirected_route_names = [
            'path.admin_add' => 'entity.path_alias.add_form',
            'path.admin_edit' => 'entity.path_alias.edit_form',
            'path.delete' => 'entity.path_alias.delete_form',
            'path.admin_overview' => 'entity.path_alias.collection',
            'path.admin_overview_filter' => 'entity.path_alias.collection',
        ];
        if (in_array($route_name, array_keys($redirected_route_names), TRUE)) {
            @trigger_error("The '{$route_name}' route is deprecated in drupal:8.8.0 and is removed from drupal:9.0.0. Use the '{$redirected_route_names[$route_name]}' route instead. See https://www.drupal.org/node/3013865", E_USER_DEPRECATED);
            static::overwriteRoute($route, $this->routeProvider
                ->getRouteByName($redirected_route_names[$route_name]));
        }
    }
    
    /**
     * Overwrites one route's metadata with the other's.
     *
     * @param \Symfony\Component\Routing\Route $target_route
     *   The route whose metadata to overwrite.
     * @param \Symfony\Component\Routing\Route $source_route
     *   The route whose metadata to read from.
     *
     * @see \Symfony\Component\Routing\Route
     */
    protected static function overwriteRoute(Route $target_route, Route $source_route) {
        $target_route->setPath($source_route->getPath());
        $target_route->setDefaults($source_route->getDefaults());
        $target_route->setRequirements($source_route->getRequirements());
        $target_route->setOptions($source_route->getOptions());
        $target_route->setHost($source_route->getHost());
        $target_route->setSchemes($source_route->getSchemes());
        $target_route->setMethods($source_route->getMethods());
    }

}