@Test
void testUTF32codes() {

    String source = "\uD842\uDF9F";
    byte[] bytes = source.getBytes(StandardCharsets.UTF_8);
    String jvmcheck = new String(bytes, 0, bytes.length, StandardCharsets.UTF_8);
    assertEquals(source, jvmcheck);
    Utf8StringBuilder buffer = new Utf8StringBuilder();
    buffer.append(bytes, 0, bytes.length);
    String result = buffer.toString();
    assertEquals(source, result);
}