// Valid changefreq
        assertTrue(sitemapsHelper.isValidChangefreq("always"));
        assertTrue(sitemapsHelper.isValidChangefreq("hourly"));
        assertTrue(sitemapsHelper.isValidChangefreq("daily"));
        assertTrue(sitemapsHelper.isValidChangefreq("weekly"));
        assertTrue(sitemapsHelper.isValidChangefreq("monthly"));
        assertTrue(sitemapsHelper.isValidChangefreq("yearly"));

    /**
     * Validates a changefreq value according to sitemap specification.
     * @param changefreq the changefreq to validate
     * @return true if valid, false otherwise
     */
    protected boolean isValidChangefreq(final String changefreq) {
        if (changefreq == null || changefreq.isEmpty()) {
            return true; // Changefreq is optional
        }
        for (final String valid : VALID_CHANGEFREQ) {