docs: protected void checkClosed() throws JMSException {
          if (getState() == CLOSED) {
              if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled())
                  SibTr.debug(this, tc, "This Connection is closed.");
              throw (javax.jms.IllegalStateException) JmsErrorUtils.newThrowable(javax.jms.IllegalStateException.class,
                                                                                 "CONNECTION_CLOSED_CWSIA0021",
                                                                                 null, tc);
          }
      }