final List<String> urlList = urlSet.stream().map(x -> x.getUrl()).sorted().toList();
            assertEquals("ftp://localhost:10021/dir1", urlList.get(0));
            assertEquals("ftp://localhost:10021/dir2", urlList.get(1));
            assertEquals("ftp://localhost:10021/text 3.txt", urlList.get(2));
            assertEquals("ftp://localhost:10021/text1.txt", urlList.get(3));