@VisibleForTesting
  @Nullable
  static Map<String, Map<String, String>> volumesSetToMap(@Nullable Set<AbsoluteUnixPath> volumes) {
    return setToMap(volumes, AbsoluteUnixPath::toString);
  }
@Test
  public void testVolumeListToMap() {
    ImmutableSet<AbsoluteUnixPath> input =
        ImmutableSet.of(
            AbsoluteUnixPath.get("/var/job-result-data"),
            AbsoluteUnixPath.get("/var/log/my-app-logs"));
    ImmutableSortedMap<String, Map<?, ?>> expected =
        ImmutableSortedMap.of(
            "/var/job-result-data", ImmutableMap.of(), "/var/log/my-app-logs", ImmutableMap.of());
    Assert.assertEquals(expected, ImageToJsonTranslator.volumesSetToMap(input));
  }