When validating correctness of the session duration value, no internal fields should be used.
That means no "configuration.SessionDuration" and no "Countly.Instance.Session._lastSessionRequestTime"
when we extend session, we send session duration, provide or default one from configuration.
"Countly.Instance.Session._lastSessionRequestTime" only keep the value when session started not duration.
I calculate duration from current time.
when we extend session, we send session duration, provide or default one from configuration. "Countly.Instance.Session._lastSessionRequestTime" only keep the value when session started not duration. I calculate duration from current time.