Java NAT Traversal

Looking for someone to implement a pure Java solution to NAT traversal. I've seen some interesting projects which seem to do just that but due to my lack of understanding of how NAT traversal works I'm having trouble implementing what they do. Running "natcracker" I can find out that my computer is accessible through "port preservation" but I'm not exactly sure how to utilize that information. I need someone to either build or use an existing solution to NAT traversal in Java. The libraries used (if used) must be commercially usable and can not force static linkage (like ice4j) as we wish to package this into an existing library. I only need a very simple client which can create sockets to communicate with another client using NAT traversal. This should not be hard with someone with experience in NAT traversal so please keep the bids appropriately priced. I do not think this project should take over $50 but I'm willing to go higher if need be. If you think you can solve this problem please PM me with the approach you could take to fix this problem.