code: public void startupSessionTimeoutCommand() {
          if (initSessionTimeoutCommand.compareAndSet(false, true)) {
              final Long sessionTimeout = getSessionTimeout();
              if ( sessionTimeout != null && sessionTimeout > 0) {
                  if ( scheduledEventslogger.isTraceEnabled() ) {
                      scheduledEventslogger.trace( "Establishing a session timeout of " + sessionTimeout + " seconds for WebSocket session (" + getId() + ").");
                  }
                  scheduleCommand(this.sessionTimeout, sessionTimeout);
              }
          }
      }
docs: Start up timer for the session timeout of the WebSocket session