/** * Handle the subscribed event. * * @param GetGroupHeaderEvent $event The event. * * @return void */ public static function handle(GetGroupHeaderEvent $event) { if ($event->getValue() !== null) { return; } $handler = new static(); $value = $handler->formatGroupHeader($event->getEnvironment(), $event->getModel(), $event->getGroupField(), $event->getGroupingMode(), $event->getGroupingLength()); if ($value !== null) { $event->setValue($value); } }