Currently groups will be synced upon a login of a groupmember.
Groups that do not contain any members (but subgroups) will not be synced.
Crowd should also fetch the parent groups of a group when adding it to the directory.

Example Use Case #1:
Group A members: Group B, Group C
Group B members: User Foo
Group C members: User Bar

Group B and C do exist. But Group A does not exist in Crowd.
And now I want to add permissions/restrictions in Confluence for Group A.

Example Use Case #2:
Group D members: User Foo, Group E
Group E members: Group F
Group F members: User Bar

Group D and F do exist. But Group E does not exist in Crowd.
And now I want to add permissions/restrictions in Confluence for Group D.
But those permissions won't apply to the members of group F, as the chain is interrupted (Group E is missing).

Compare to CWDSUP-5870