Ah, so now we're mixing JAXB into the whole thing as well.
The problem I guess is that JAXB 1.0 doesn't work very well with Java 6 and so therefore you should update JAXB as well, however the JAXB API might have changed between 1.0 and whatever you're upgrading to so you need to alter your code to work with the new version of JAXB.
Sounds very simple but it all depends on how much JAXB stuff you are using. The only way to solve this then is to go through your code and try to find some way in the new JAXB to replace your old code with. Something that probably does what you want and maybe even faster.
So in relation to your initial post, the classes/interfaces will most likely have disappeared and you need to find the new JAXB replacements. What are you using JAXB for doing? Are you just marshalling Java objects into XML and back?
// Json