The deployment of a minimal Enterprise Application Project (consisting of e.g. jboss-seam.jar as ejb-module and mvel2.jar as 3rd-party jar) with the deployment option "Deploy projects as compressed archives" activated, results in an ear containing some invalid jars: These invalid jars are containing only one jar with the same name which finally contains the actual jar content.
E.g. the mvel2.jar contains a mvel2.jar which contains the "META-INF" and an "org" directory.

It seems that every supplied jar is affected that is determined as module jar, because it is an ejb-module (e.g. jboss-seam.jar) or its manifest contains a "Main-class" entry marking it as client-module.