public function writeXml(\XMLWriter $xmlWriter)
    {
        $content = null;
        if (!is_null($this->_topicDescription)) {
            $content = new Content();
            $content->setText(
                XmlSerializer::objectSerialize(
                    $this->_topicDescription,
                    'TopicDescription'
                )
            );
            $content->setType(Resources::XML_CONTENT_TYPE);
        }
        $this->_entry->setContent($content);
        $this->_entry->writeXml($xmlWriter);
    }