public static SpecificData get() {
    return INSTANCE;
  }
@Test
  void nonStringable() throws Exception {
    final Schema string = Schema.create(Type.STRING);
    final ByteArrayOutputStream baos = new ByteArrayOutputStream();
    final Encoder encoder = EncoderFactory.get().directBinaryEncoder(baos, null);
    final DatumWriter<Object> writer = new SpecificDatumWriter<>(string);
    try {
      writer.write(new Object(), encoder);
      fail("Non stringable object should be rejected.");
    } catch (ClassCastException cce) {
      // Expected error
    }
  }