The AsynCounter and SyncCounter interfaces were supposed to be temporary in JGroups RAFT until they are stable [1].

No more changes are planned to them, so merge them in JGroups.

[1] https://github.com/belaban/jgroups-raft/blob/8e1b052ba7e610fee2c4169bb85a5691cdede97c/src/org/jgroups/blocks/atomic/package-info.java#L2