public static StringSetResult create(Set<String> s) {
    return new AutoValue_StringSetResult(ImmutableSet.copyOf(s));
  }
@Test
  public void create() {
    // Test that create makes an immutable copy of the given set
    HashSet<String> modifiableSet = new HashSet<>(Arrays.asList("ab", "cd"));
    StringSetResult stringSetResult = StringSetResult.create(modifiableSet);
    // change the initial set.
    modifiableSet.add("ef");
    SetView<String> difference = Sets.difference(modifiableSet, stringSetResult.getStringSet());
    assertEquals(1, difference.size());
    assertEquals("ef", difference.iterator().next());
    assertTrue(Sets.difference(stringSetResult.getStringSet(), modifiableSet).isEmpty());
  }