Unfortunately I still need Java 5 and it would be quite some effort to port the projects to Sun’s Java 6, especially the QA and customer roll-out would be terribly intricate. Somebody on ubuntuforums.org posted the idea to port the Jaunty release.
That’s what I did now. Downloaded the Jaunty source packages and build new ones on my Karmic box.
This works perfectly fine for me and I’ll try to put the files in a repository soon in case anybody else is in the same position.