ImmutableList.Builder<String> httpHeaders = ImmutableList.builder();
    for (Field field : httpHeadersFields()) {
      httpHeaders.add((String) field.get(null));
    }
    assertThat(httpHeaders.build()).containsNoDuplicates();
  }

  private static ImmutableSet<Field> httpHeadersFields() {
    ImmutableSet.Builder<Field> builder = ImmutableSet.builder();
    for (Field field : HttpHeaders.class.getDeclaredFields()) {
      /*

      } 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