public function addChoiceSite(SiteFormEvent $event)
    {
        $builder = $event->getBuilder();
        $subGroupRender = $builder->getAttribute('sub_group_render');
        $subGroupRender = array_merge($subGroupRender, array(
            'media' => array(
                'rank' => 2,
                'label' => 'open_orchestra_media_admin.form.site.sub_group.media',
            ),
        ));
        $builder->setAttribute('sub_group_render', $subGroupRender);

        $builder->addEventSubscriber($this->mediaLibrarySharingSubscriber);
    }