} else {
        assertThat(charset).isAbsent();
      }
    }
  }

  @J2ktIncompatible
  @GwtIncompatible // reflection
  public void testConstants_areUnique() {
    assertThat(getConstants()).containsNoDuplicates();
  }

  @J2ktIncompatible
  @GwtIncompatible // reflection
  private static FluentIterable<Field> getConstantFields() {
    return FluentIterable.from(asList(MediaType.class.getDeclaredFields()))

  public void testRemoveIf_randomAccess_notPermittingDuplicates() {
    // https://github.com/google/guava/issues/1596
    List<String> uniqueList = newArrayList("a", "b", "c", "d", "e");
    assertThat(uniqueList).containsNoDuplicates();

    assertTrue(uniqueList instanceof RandomAccess);
    assertTrue(
        removeIf(
            uniqueList,
            new Predicate<String>() {
              @Override