How to check if a session is invalid

Question

How to check if a session is invalid or not? There is no method in the API.

Is it the same as isNew()? And what is the difference if not?

Answer 1

isNew() is true only if this session wasn't yet accepted by client (i.e. it was just created, and JSESSIONID wasn't sent yet, or if it was sent, client didn't send it back, so server doesn't know about it and created another session)