/**
     * Registers the form resources for the Twig templating engines.
     *
     * @param \Symfony\Component\DependencyInjection\ContainerBuilder $container The container.
     */
    protected function registerResources(ContainerBuilder $container)
    {
        $templatingEngines = $container->getParameter('templating.engines');

        if (in_array('twig', $templatingEngines)) {
            $twigFormResources = $container->hasParameter('twig.form.resources')
                ? $container->getParameter('twig.form.resources')
                : [];

            $container->setParameter(
                'twig.form.resources',
                array_merge(
                    $twigFormResources,
                    [
                        'RoboAdminMenuBundle:Form:admin_menu_entity_widget.html.twig',
                        'RoboAdminMenuBundle:Form:admin_class_choice_widget.html.twig',
                    ]
                )
            );
        }
    }