public function setSubscribers($subscribers)
    {
        //flatten the array
        $subscribers = AnHelperArray::getValues(AnConfig::unbox($subscribers));
        $ids = array();

        foreach ($subscribers as $subscriber) {
            if (is($subscriber, 'AnDomainEntityAbstract')) {
                $ids[] = $subscriber->id;
            } else {
                $ids[] = $subscriber;
            }
        }

        $ids = array_unique($ids);

        if (!empty($ids)) {
            $this->set('subscriberIds', AnDomainAttribute::getInstance('set')->setData($ids));
        } else {
            $this->delete();
        }

        return $this;
    }