Thanks Jaikiran for the quick reply.
It looks like JForum3 combines some old lib(like Lucene, commons-lang) and some new (like vraptor 3.4), some deprecated features were used, so the exact version of jar files have to be there to make it compile.
I also see things like groovy were there, which sounds not mentioned in the design discussion
thread. Do you know whether I can find an updated document for the current design?
JForum3 used a lot of new interesting stuff and code is nice and clean. If there is a full compilable version available, it would save a lot of time(like finding and downloading the exact jars) for anybody who want to contribute to the project.
Thanks again!