public static Configuration unix() {
    return UnixHolder.UNIX;
  }
@Test
  public void testFileSystemWithDefaultWatchService() throws IOException {
    FileSystem fs = Jimfs.newFileSystem(Configuration.unix());

    WatchService watchService = fs.newWatchService();
    assertThat(watchService).isInstanceOf(PollingWatchService.class);

    PollingWatchService pollingWatchService = (PollingWatchService) watchService;
    assertThat(pollingWatchService.interval).isEqualTo(5);
    assertThat(pollingWatchService.timeUnit).isEqualTo(SECONDS);
  }