Define the exact implementation of the HttpSession to be used

[Idrinth]

https://docs.oracle.com/javaee/6/api/javax/servlet/http/HttpSession.html
This is required to properly serialize it outside java applications and likely inside as well, you might want to put a thrift-ready implementation into a repository of it's own.
(as in the way to store data, not necessarily the function implementations besides the session id)