public static <K, V> ProducerRecordCoder<K, V> of(Coder<K> keyCoder, Coder<V> valueCoder) {
    return new ProducerRecordCoder<>(keyCoder, valueCoder);
  }
@Test
  public void testCoderIsSerializableWithWellKnownCoderType() {
    CoderProperties.coderSerializable(
        ProducerRecordCoder.of(GlobalWindow.Coder.INSTANCE, GlobalWindow.Coder.INSTANCE));
  }