* Gets the XPath API instance for this thread.
     *
     * @return the XPath API instance
     */
    protected XPathAPI getXPathAPI() {
        XPathAPI cachedXPathAPI = xpathAPI.get();
        if (cachedXPathAPI == null) {
            cachedXPathAPI = new XPathAPI();
            xpathAPI.set(cachedXPathAPI);
        }
        return cachedXPathAPI;
    }

    /**