code: private void setInactivityTimer(long ms) {
          if (sessionInactivityTimer == null) {
              sessionInactivityTimer = new SessionInactivityTimer(sessionHandler.getScheduler(), this);
          }
          sessionInactivityTimer.setIdleTimeout(ms);
      }
docs: Set the session inactivity timer.
  
  @param ms value in millisec, -1 disables it