final String xpath = xpathConfigMap.get(XPath.DEFAULT_DIGEST);
        if (StringUtil.isNotBlank(xpath)) {
            return xpath;
        }
        return fessConfig.getCrawlerDocumentHtmlDigestXpath();
    }

    /**
     * Extracts the canonical URL from the HTML document.
     *
     * @param responseData the response data from crawling
     * @param document the parsed HTML document