I downloaded the add-on project from github. There was a type conflict (AbstractComponentContainerState is expected in 8.0) while the project uses AbstractComponentState.
Since the former is a pass through for the latter, swapping these two seems a safe bet. It compiled despite the guava warning. If I get it to work with 8.0, I will put a pull request for the change.
No, this simple change did not do the trick. I decided to port the code to Java 8, and remove all the references to xtend. I got it to a point where there was an exception because a parent in the container chain was null or somtehing along those lines.
When I have a little bit more time, I will post my progress/work