Make author filtering in search screen usable in hosted environment

The author filtering work done for Confluence 2.9 search screen is not usable in the hosted environment. For a couple of reasons I believe -

1) PersonalInformation objects are not indexed
2) Even if PersonalInformation was indexed the auto-complete box would be offering all users on that instance. This would be a security leak in the hosted environment.

I had a quick chat with Jens and off the top of his head he suggests that indexing 'SpaceGroups' along with the PersonalInformation and filtering the search of PersonalInformation documents by SpaceGroups may solve the issue.