I apologize if this is answered in a FAQ somewhere.
Are the module source code available somewhere? Are they controlled by the original author? Say a module owner is no longer interested in maintaining a game–is there a way to change management of the code for that module?
This is something we don’t have a formal policy on. If you’re talking about custom Java classes for a module, most of those I’ve seen have been released without any license information (which is bad practice, but I think most module designers aren’t aware that they should).
If you’re just talking about maintainership for a module—module pages in the wiki should list who the current module maintainer is. Lots of modules don’t have maintainers right now. I suspect that players would be grateful to have their modules maintained if you wanted to volunteer.