public function handleBlameTimestamp(PreIndexEvent $event)
    {
        $subject = $event->getSubject();
        $document = $event->getDocument();

        if ($subject instanceof UserBlameInterface) {
            $this->mapCreatorAndChanger($document, $subject->getCreator(), $subject->getChanger());
        }

        if ($subject instanceof TimestampableInterface) {
            $this->mapTimestamp($document, $subject->getCreated(), $subject->getChanged());
        }
    }