* This pattern is utilized by the extractor to identify and process XML elements.
     *
     * @return the {@link Pattern} instance for XML tag matching
     */
    @Override
    protected Pattern getTagPattern() {
        return xmlTagPattern;
    }

    /**
     * Returns the XML encoding pattern.
     * @return The XML encoding pattern.
     */
    public Pattern getXmlEncodingPattern() {

     */
    protected abstract Pattern getEncodingPattern();

    /**
     * Returns the pattern used to identify tags in the content.
     * @return The tag pattern.
     */
    protected abstract Pattern getTagPattern();

    @Override
    public ExtractData getText(final InputStream in, final Map<String, String> params) {
        if (in == null) {
            throw new CrawlerSystemException("The inputstream is null.");

        return metaCharsetPattern;
    }

    /*
     * (non-Javadoc)
     *
     * @see org.codelibs.fess.crawler.extractor.impl.AbstractXmlExtractor#getTagPattern()
     */
    @Override
    protected Pattern getTagPattern() {
        return htmlTagPattern;
    }

    /**
     * Gets the pattern used for extracting charset from meta tags.
     *
     * @return the meta charset pattern

        return metaCharsetPattern;
    }

    /*
     * (non-Javadoc)
     *
     * @see org.codelibs.fess.crawler.extractor.impl.AbstractXmlExtractor#getTagPattern()
     */
    @Override
    protected Pattern getTagPattern() {
        // not used
        return null;
    }

    /**
     * Adds a feature to the extractor.
     *
     * @param key   the key of the feature