The j2objc-discuss Google group is an email forum for J2ObjC-related discussions, project feedback, and insights into project direction and issues. If you hit a roadblock, searching that forum will often find developers with similar issues, along with solutions or workarounds.
Questions and answers are also found on StackOverflow, using the j2objc tag. This forum is proving very useful, as knowledgeable Java and Objective C developers who don't use J2ObjC often provide answers.
Bug and Enhancement Reports
J2ObjC's issues list reported problems and suggestions.
All source code is found on GitHub in the google/j2objc project.