This should work (at least, the test-suite passes).
This is our first java library, and we're newbies,
so be kind and do patch what's gouging your eyes.
This implementation is score-based, for performance.
There are many other ways of implementing MJ.
There is no support (yet) for a default grade,
but you can do it yourself while building the tally.
Special thanks to @plguhur for the assistance,
and the whole MieuxVoter operational team.