if an artifact in the list of ear modules already exists in the ear, the ear mojo will copy it on top of itself, zeroing out the file

The ear plugin doesn't check for artifacts that are already deployed within the ear, and so ends up redundantly copying such artifacts, e.g.:

copy C:/appserver/deploy/my.ear/lib/my.jar C:/appserver/deploy/my.ear/lib/my.jar

and when you copy a file onto itself using the Plexus copy util method, it zeros out the file (a bug in itself IMO but that's beside the point .

A check should be added, so the ear plugin intelligently handles this, albeit unusual, case.