public function writeInnerXml(\XMLWriter $xmlWriter)
    {
        Validate::notNull($xmlWriter, 'xmlWriter');

        $this->writeOptionalAttribute($xmlWriter, 'href', $this->href);
        $this->writeOptionalAttribute($xmlWriter, 'rel', $this->rel);
        $this->writeOptionalAttribute($xmlWriter, 'type', $this->type);
        $this->writeOptionalAttribute($xmlWriter, 'hreflang', $this->hreflang);
        $this->writeOptionalAttribute($xmlWriter, 'title', $this->title);
        $this->writeOptionalAttribute($xmlWriter, 'length', $this->length);

        if (!empty($this->undefinedContent)) {
            $xmlWriter->writeRaw($this->undefinedContent);
        }
    }