a) promise that he is author -- court says "such a simple claim is not enough"
b) point towards the git repository where everybody can see his contributions -- court says "you have to prove that you're author, not just give instructions how other people could prove it"
c) say that kernel version x.y.z is "closest" to VMware software -- court says "don't just throw a version string at us, show with concrete examples which code passages have been lifted"
And some more things along these lines.
I'm really confused how Hellwig's lawyer even tried that. Even to a layperson it's obvious that "I won't prove my authorship, but if the court wishes to do itself, it will be easy" won't fly.