gistfile1.java

		 
    Stream<MessageAndMetadata<byte[], byte[]>> stream = StreamSupport.stream(Spliterators.spliteratorUnknownSize(iterator, Spliterator.ORDERED), false);
		while (true) {
			stream.parallel().map(d -> {
					byte[] value = d.message();
					Message msg = message.newBuilderForType().mergeFrom(value, 0, value.length).build();
				  return 1; // I would actuall extract a field from the message and return it, keeping it simple here
			}).sum();
		}