private function registerSocialSubjectEventSubscriber(ContainerBuilder $container)
    {
        $definition = new Definition('Ekyna\Bundle\CmsBundle\EventListener\SocialSubjectEventListener');
        $definition->addArgument(new Reference('ekyna_cms.helper.page'));
        $definition->addArgument(new Reference('router'));
        $definition->addTag('kernel.event_subscriber');
        $container->setDefinition('ekyna_cms.social_subject_event_listener', $definition);
    }