Just an idea popped in my head.
Wouldn't it be useful if ShrinkWrap creates "default" MANIFEST.MF if user didn't call setManifest method or better said if there is not file called MANIFEST.MF ?
By default I mean something like:
Created-By: 1.0.0 (ShrinkWrap)
It looks useful to me or at least it will create complete archive.
I've created a ManifestAsset class that you can find on github:
Using it right now is possible to add all the main attributes in a JAR Manifest.
I did it for work and because I wanted to try git but I would be happy to contribute to the project and change whatever you think is wrong.
Thanks for the great work,