Not sure if schema requirements changed but it is no longer valid to
use:
Schema({}, extra=True)
The docs say that should be avoided and instead you should use:
Schema(dict)
To indicate a dict that can have any key: value pairs. Additionally
extra=True appears to be replaced with extra=ALLOW_EXTRA so update that
in cases where we have some subset of desired keys.
Change-Id: Ia9f4d535b9b633e703465f155c4722d9a58c45a7
0a38b6c568