Please anyboidy explain me meaning of following lines as given in
Servlet Specs
If distributed containers persist or migrate sessions to provide quality of
service features, they are not restricted to using the native JVM Serialization
mechanism for serializing HttpSessions and their attributes. Developers are not
guaranteed that containers will call readObject and writeObject methods on
session attributes if they implement them, but are guaranteed that the
Serializable closure of their attributes will be preserved.