Support for Java 6 ends in summer 2012.
Support for Java 5 should also be dropped, EOL was long ago.
Please update JRE to 7u51.
I'll be fixing this once the bamboo fiasco clears. I've been poking around and see how things are working now, I hope.
It will be nice to have a ticket always open, when you release a new version, always update Java JRE version in the same time!
Relevant build logs
I don't like keeping the same ticket open forever. This will mean it isn't resolved for many years. I think after closing laast one, new one must be filed for the next Openfire release. Though, updating Java to the latest version (which can be a few days old) when doing a release can be risky. I don't remember new Java version causing troubles to Openfire, but in desktop versions it sometimes does.