Well you could just write one, if you can't find a clean open source version?
btw why do you need PacMan? is it for learning?
if you just need source code for learning the basics of how you would write a game in Java, I'd say have a look at the excellent Space Invaders tutorial over at http://www.cokeandcode.com/spaceinvaderstutorial
its very good for learning.
There are good reasons I haven't stepped up and written one myself
I'm developing a new game framework for my research, and part of the story of my paper is to say "this works on games people have actually written, I haven't just written ones myself that happen to work with this thing." This ideally requires me to use others' code for it.
It's funny you should mention that Space Invaders game, as that is the first game I adapted to the framework, and it worked! I now need to take a step up in complexity, which is where PacMan came in. This has AI opponents, as well as movement constraints and such, that make it interesting. By complexity, I am specifically looking at the rules
of the game. While say, Asteroids, can be quite complicated, much of it is a geometry problem, not a game design
PacMan isn't a requirement, just something along that sort of complexity, with a recognizable game to someone who will never play it (they'll just read the paper). I've been trying to get PacDasher to work, but it's reliance on an old XML parser library that doesn't exist (JDOM instead of W3C DOM) means the entire XML parser would have to be rewritten to build, which is a pain, given that the code is already pretty complicated