@J2ktIncompatible
  @GwtIncompatible // Non-UTF-8 Charset
  public void testGetCharset_utf16() {
    assertThat(MediaType.parse("text/plain; charset=utf-16").charset()).hasValue(UTF_16);
  }

  public void testGetCharset_tooMany() {
    MediaType mediaType = MediaType.parse("text/plain; charset=utf-8; charset=utf-16");
    assertThrows(IllegalStateException.class, mediaType::charset);
  }

  public void testGetCharset_illegalCharset() {