protected function serializeArticle(ArticleInterface $object, $pageNumber)
    {
        return $this->get('jms_serializer')->serialize(
            $object,
            'array',
            SerializationContext::create()
                ->setSerializeNull(true)
                ->setGroups(['website', 'content'])
                ->setAttribute('website', true)
                ->setAttribute('pageNumber', $pageNumber)
        );
    }