Updated openstack/openstack
Project: openstack/ceilometer  77e8a9d4d070b5983813f1dad42e28e2f0123947

Use None instead of mutables in method params default values

Mutables in the method params defaults might cause errors and
that's why it's anti-pattern in most of the cases and should be
removed.

Change-Id: Ib1498e68ab9cc770b237a324b733c85b4a5c6839