code: public function handleRelationChange(RelationshipEvent $event)
      {
          if (get_class($event->parentObject) === $this->owner->primaryModel) {
              Cacher::invalidateGroup('aros');
          }
      }
docs: [[@doctodo method_description:handleRelationChange]].
  
  @param cascade\components\types\RelationshipEvent $event [[@doctodo param_description:event]]