final SitemapSet sitemapSet = sitemapsHelper.parse(in);
        final Sitemap[] sitemaps = sitemapSet.getSitemaps();

        // Should parse successfully, ignoring unknown elements
        assertEquals(1, sitemaps.length);
        assertEquals("http://www.example.com/page1.html", sitemaps[0].getLoc());
        assertEquals("2025-01-01", sitemaps[0].getLastmod());
    }