public function testRequiredClassesValidChildren()
{
$articleFolder = new CmsArticleFolder();
$articleFolder->id = '/functional/articles';
$article = new CmsArticle();
$article->id = '/functional/articles/article';
$article->topic = 'greetings';
$article->text = 'Hello World';
$this->dm->persist($articleFolder);
$this->dm->persist($article);
$this->dm->flush();
}