public function routeClass($routeClass = null)
    {
        deprecationWarning(
            'RouteBuilder::routeClass() is deprecated. ' .
            'Use RouteBuilder::setRouteClass()/getRouteClass() instead.'
        );
        if ($routeClass === null) {
            return $this->getRouteClass();
        }
        $this->setRouteClass($routeClass);
    }