I would much prefer not to roll back to grails 1.3.9. We have a lot of code written under grails 2.0.x and I suspect that a major rollback like that would be very painful. otoh, after forking drools-gorm and looking at bringing it up to date, I find that the drools/jbpm/hibernate environments are rather different than assumed in drools-gorm so that could be just as much effort.
<sigh> already lost 3 days this week, which puts me at least a month behind schedule. I didn't need this extra aggravation...
It turns out that excluding hibernate-annotations prevents this particular problem. I don't know if any other problems remain because we just removed use of drools-gorm and reference drools jars directly.