private function grouppedNotification(&$group, &$queue)
    {
        if (is_object($group) === false) {
            return;
        }
        if (intval($group->group_notifications) === 0) {
            return;
        }

        foreach ($queue as &$item) {
            $item->complete();
        }

        $this->trigger(
            self::EVENT_DEFERRED_QUEUE_GROUP_COMPLETE,
            new DeferredQueueGroupCompleteEvent($queue, $group)
        );
    }