*/
    protected Map<String, String> featureMap = new HashMap<>();

    /** Map of properties for the DOM parser. */
    protected Map<String, String> propertyMap = new HashMap<>();

    /** XPath expression to select target nodes for text extraction. */
    protected String targetNodePath = "//HTML/BODY | //@alt | //@title";

    /** Cache for XPathAPI instances to improve performance. */

     * Extracts URLs from HTML tag attributes using XPath.
     *
     * @param url the base URL for resolving relative URLs
     * @param document the document to extract URLs from
     * @param xpath the XPath expression to select elements
     * @param attr the attribute name to extract URLs from
     * @param encoding the character encoding to use
     * @return a list of extracted URLs
     */