About politics: packaging Java stuff changes nothing to the rules Debian uses to find if a program is free or not. Since there are not many free Java tools, keep in mind the following:
If your source package can compile (correctly) only with non-free tools, it cannot go to main. If your package itself is free, it must go to contrib.
If your binary package can run only with non-free virtual machines (GNU-Classpath has a list of free versions), it cannot go to main. If your package itself is free, it must go to contrib. Since java libraries do not have a runtime dependency, this rule does not apply to them.