protected function getEventSubscribers()
    {
        $eventSubscribers = $this->getOption('event_subscribers');

        if (is_null($eventSubscribers) || !is_array($eventSubscribers)) {
            return;
        }

        return array_filter(
            $eventSubscribers,
            function ($subscriber) {
                return $subscriber instanceof EventSubscriber;
            }
        );
    }