Basically anything except GPL and AGPL should be ok.
http://opensource.org/licenses
To avoid confusions, I would suggest sticking to one of:
Apache
BSD
or possibly LGPL, if you want to force people to contribute back changes to your library, but don’t expect them to open source rest of the code. But probably BSD is safest choice, given that jme3 is BSD and people are contributing back to it anyway…