Then if you're going between versions, you can avoid having to update the lion's share of code just because the dependencies change.
jabberwork-1.2
jabberwock.core-1.6
jabberwock.apache.interface-0.3
jabberwock-1.3
jabberwock.core-1.6
jabberwock.apache-interface-0.4
Instead of having to update all the hefty ".core" modules, you could get away with only updating the hopefully lighter launchers / library loaders and the specific interface code being updated.