Since the young gen cset group is part of the collection set, actions taken on the other parts of the collection set (non young gen cset groups) are always done together with the young gen cset group.

Currently the pattern is:
- do something for the collection set
- do something for the young gen group

at the same code level.

It would be preferred if the G1CollectionSet class took over management of the young gen cset group, i.e. including the young gen cset group with actions on the "other" collection set.