I am using your great uberwar packaging type to merge severals wars.
I do it in two steps : first merging 2 wars, then merging the resulted war with another war.
(Please dont tell me to merge the 3 wars in one time, this is not what I want to do, for code mutualisation reasons)
So the first merge by uberwar works great, but the second fails with "Exception during merging web.xml"
Looking at your sources, the second merge cannot find the "web.xml" file in the war produced by the first merge.
This, because it searchs for "WEB-INF/web.xml" as a ressource part of the war, and uberwar creates, on Windows plateforms, war with "WEB-INF\web.xml"
I suggest, and patch is attached, to bypass the file.separator plateform setting, to create war achives with '/' as path separator in entry names, as the plexus/AbstractZipArchiver do