MediaType.create(constant.type(), constant.subtype())
              .withParameters(constant.parameters()));
    }
  }

  @J2ktIncompatible
  @GwtIncompatible // reflection
  public void testConstants_charset() throws Exception {
    for (Field field : getConstantFields()) {
      Optional<Charset> charset = ((MediaType) field.get(null)).charset();
      if (field.getName().endsWith("_UTF_8")) {