added a comment - - edited
copy problem looks a lot like unpack problem, but has a major difference: when unpack finds a directory, copying it ressembles a lot to unpacking packaged artifact (if no classifier and nothing generated during packaging)
but if copy finds a directory, what is it expected to do? copy the directory (even if expected result is a file)? create a zip file with the directory content? create a jar file (what to do with the Manifest?)? fail? ignore with warning?
this seems like there is no solution other than require to package first, or we'll get an approximation that can be more problematic than a clear failure