Requests for persistent sessions always trigger replication

For persistent sessions, we trigger session session activation events after a successful SessionManager.findSession(...). However, this is currently triggered using a Session instance, instead of an ImmutableSession instance, which causes iteration over session attributes to trigger replication of the session at the end of the request - even when the user does not access any mutable session attributes.

The same is true for Session.close() (via session passivation event).