Append users(instances) in Volume.extra
@@ -8540,6 +8540,7 @@ class GCENodeDriver(NodeDriver):
extra['sourceSnapshotId'] = volume.get('sourceSnapshotId')
extra['options'] = volume.get('options')
extra['licenses'] = volume.get('licenses')
+ extra['users'] = volume.get('users')
extra['type'] = volume.get('type', 'pd-standard').split('/')[-1]
