Unfortunately, when validate-jars was put back in, an override mechanism wasn't added so you're stuck manually editing the build file for now.
I'll be submitting a patch to first of all add the override mechanism so that this won't trip people up until the target is fixed.
Umm... I fear I fixed the reason of the issue... I haven't change build to make validation optional - this will keep document more up-to-date.
Vadim
