完美解决方案:
http://stackoverflow.com/questions/18442753/a-required-class-was-missing-while-executing-org-apache-maven-pluginsmaven-war
this happened to me too after adding the version tag, that was missing, to the maven-war-plugin (not sure what version was using by default, i changed to the latest, 2.6 in my case). I had to wipe .m2/repository to have the build succeed again.
I tried first to clean the maven-filtering folder (in the repo) but then instead of a MavenFilterException i was getting an ArchiverException. So i concluded the local repository was corrupted (for a version upgrade?) and i deleted everything.
That fixed it for me. Just clean your local repo.