public function handleCopy(CopyEvent $event)
    {
        $document = $event->getDocument();
        if (!$document instanceof ArticleDocument) {
            return;
        }

        $uuid = $event->getCopiedNode()->getIdentifier();
        $this->documents[$uuid] = [
            'uuid' => $uuid,
            'locale' => $document->getLocale(),
        ];
    }