private function findWritingLockMeta(ArticleInterface $article)
    {
        $metaLock = null;

        //search writing_lock data
        foreach($article->getMetaData() as $meta)
        {
            if($meta->getKey() == 'writing_locked')
            {
                $metaLock = $meta;

                break;
            }
        }

        return $metaLock;
    }