protected function getPostTypes()
 {
     if (false === $this->post_types) {
         require_once vc_path_dir('SETTINGS_DIR', 'class-vc-roles.php');
         $vc_roles = new Vc_Roles();
         $this->post_types = $vc_roles->getPostTypes();
     }
     return $this->post_types;
 }