protected function getEventListeners($event = null): array
    {
        $eventManager = $this->getEventManager();

        return $event !== null && !$eventManager->hasListeners($event) ? [] : $eventManager->getListeners($event);
    }
protected function getEventListeners($event = null): array
    {
        $eventManager = $this->getEventManager();

        return $event !== null && !$eventManager->hasListeners($event) ? [] : $eventManager->getListeners($event);
    }
protected function getEventListeners ( $ event = null ) : array { $ eventManager = $ this -> getEventManager ( ) ; return $ event !== null && ! $ eventManager -> hasListeners ( $ event ) ? [ ] : $ eventManager -> getListeners ( $ event ) ; }
Get event listeners.

@param string|null $event

@return EventSubscriber[]
Get event listeners .