The Google issue was just closed with [a comment](https://code.google.com/p/google-compute-engine/issues/detail?id=111#c5) that this field is indeed consider optional, so our code change here should be good to stay.
--- Reply to this email directly or view it on GitHub: https://github.com/jclouds/jclouds-labs-google/pull/49#issuecomment-59357140
