How to convert two longs to a byte array = how to convert UUID to byte array?

I am using Javas UUID and need to convert a UUID to a byte Array. Strangely the UUID Class does not provide a "toBytes()" method.

I already found out about the two methods:

UUID.getMostSignificantBits()
and
UUID.getLeasSignificantBits()

But how to get this into a byte array? the result should be a byte[] with those tow values. I somehow need to do Bitshifting but, how?

update:

I found:

 ByteBuffer byteBuffer = MappedByteBuffer.allocate(2);
 byteBuffer.putLong(uuid.getMostSignificantBits());
 byteBuffer.putLong(uuid.getLeastSignificantBits());

Is this approach corret?

Are there any other methods (for learning purposes)?

Thanks very much!! Jens