private static final String PRIORITY_ELEMENT = "priority";

        private static final String CHANGEFREQ_ELEMENT = "changefreq";

        private static final String LASTMOD_ELEMENT = "lastmod";

        private static final String LOC_ELEMENT = "loc";

        private static final String URL_ELEMENT = "url";

        private SitemapSet sitemapSet;

        private SitemapUrl sitemapUrl;