code: public int compare(ByteBuffer o1, ByteBuffer o2)
      {
          if (!o1.hasRemaining() || !o2.hasRemaining())
              return o1.hasRemaining() ? 1 : o2.hasRemaining() ? -1 : 0;
  
          return UUIDGen.getUUID(o1).compareTo(UUIDGen.getUUID(o2));
      }
docs: singleton