The user data is typically a pointer to a data structure or a handle which
may no longer be valid after the session is restored. If the user data needs
to be preserved, let the application do it. This way, it is a conscious
decision for the application to save/restore either the pointer/handle
itself or the object it refers to.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>