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

  public void testGetCharset_illegalCharset() {
    MediaType mediaType = MediaType.parse("text/plain; charset=\"!@#$%^&*()\"");
    assertThrows(IllegalArgumentException.class, mediaType::charset);
  }