code: void checkNotClosed() throws JMSException {
          int currentState;
          synchronized (stateLock) {
              currentState = state;
          }
          if (currentState == CLOSED) {
              throw (javax.jms.IllegalStateException) JmsErrorUtils.newThrowable(javax.jms.IllegalStateException.class,
                                                                                 "SESSION_CLOSED_CWSIA0049",
                                                                                 null,
                                                                                 tc
                              );
          }
      }
docs: This method is called at the beginning of every method that should not
  work if the Session has been closed. It prevents further execution by
  throwing a JMSException with a suitable "I'm closed" message.