/**
  * Return available bidirectional object names
  *
  * @return array Bidirectional object names
  * @since 2.3.4
  */
 public function bidirectional_objects()
 {
     if ($this->setup_related_objects() || null === self::$names_bidirectional) {
         $bidirectional_objects = array();
         foreach (self::$related_objects as $object => $related_object) {
             if (!isset($related_object['bidirectional']) || !$related_object['bidirectional']) {
                 continue;
             }
             $bidirectional_objects[] = $object;
         }
         self::$names_bidirectional = (array) apply_filters('pods_form_ui_field_pick_bidirectional_objects', $bidirectional_objects);
     }
     return self::$names_bidirectional;
 }