Contao\CoreBundle\Routing\FrontendLoader::addFrontendRoute PHP Method

    private function addFrontendRoute(RouteCollection $routes, array $defaults)
    {
        $route = new Route('/{alias}%contao.url_suffix%', $defaults, ['alias' => '.+']);
        $this->addLocaleToRoute($route);
        $routes->add('contao_frontend', $route);
    }