eclipse:to-maven produces unusable jars (jars containing jars)

The eclipse install contains plugins that are actually directories, which contain the plugin.xml etc and a jar file (for example: org.hibernate.eclipse_3.2.3.GA, org.junit4_4.3.1) or more than one jar file (e.g. org.eclipse.emf.teneo.hibernate_1.0.1.v200809211527)

eclipse:to-maven simply jars up the directory when it puts it in the repository, which means all the classes in the jar(s) inside are unreachable.

I am not sure what a suitable behaviour is - I have expanded the jars in org.eclipse.emf.teneo.hibernate_1.0.1.v200809211527 and re-jarred it and it then works fine in maven, so this may be a (optional) solution.