private function getCollectionByContent($contentUid, MediaFolder $mediaFolder)
    {
        $content = $this->getEntityManager()->find('BackBee\ClassContent\AbstractClassContent', $contentUid);

        if (null === $content) {
            throw new NotFoundHttpException("No content find with uid '{$contentUid}'");
        }

        return $this->getMediaRepository()->getMediasByContent($content, $mediaFolder);
    }