Build issue generating .jars

Hello people,

I am having hard time debugging one problem, and I hope some might be able
to shed a light on it.

In openSUSE our build service is producing us the LO builds, and sometimes
it gets result like [1].

This means some of the .jar files are produced empty with just MANIFEST.MF
files inside them. The problem with it being random is even if I do local
checkout and build it localy on my machine it is built fine and I actually
didn't ever manage to get it fail like in the [1].

I think there are 2 issues:
1) it fails randomly, which should be fixed
2) it fails silently and continues with empty jars, this is more fatal, and
there should be some check if the java generated what is expected.

Any ideas what is happening? I am really lost here :(

TIA

Tom

[1] https://bugzilla.suse.com/show_bug.cgi?id=913042