Jar resources detect zip that are not signed

[fstn]

Hi, I trying to use maven webstart plugin download servlet. And I have this issue:

The number of signed artifacts (1) differ from the number of modified artifacts (2). Implementation error -> [Help 1]

This issue is due to the fact that resource.zip is adding to the modifiedJnlpArtifacts list but not signed.
I think that zip files must be ignored from jar resources.

Change can be done on JnlpDownloadServletMojo on line 551.