suspend method
Invoked when the session is suspended.
This method is invoked after the HTTP response has been produced for a HTTP request.
This method can be implemented by subclasses of Session to perform operations on the session at the end of using it in handling a HTTP request. For example, to persist its state to a database. After this, the Session will not be used again until it is restored for another HTTP request or it is terminated by the timeout timer.
The base implementation does nothing.
Note: this method is only automatically invoked if the session is set on the Request at the end of providing the response for it. If the handler removes the session from the Request, this method is not automatically invoked. For example, when a session is cleared because the user has logged out. In that situation, if this method needs to be invoked, the handler should explicitly invoke it.
This instance method is intended to be overridden by subclasses of the Session class.
Implementation
Future suspend(Request req) async {
// do nothing
}