docs: public void startNewSystemThread(Runnable runnable)
                      throws InterruptedException {
          if (TraceComponent.isAnyTracingEnabled()
              && tc.isEntryEnabled())
              SibTr.entry(tc, "startNewSystemThread", runnable);
  
          if (_systemThreadPool == null) {
              createSystemThreadPool();
          }
  
          try {
              _systemThreadPool.execute(runnable,
                                        ThreadPool.EXPAND_WHEN_QUEUE_IS_FULL_WAIT_AT_LIMIT);
          } catch (ThreadPoolQueueIsFullException e) {
              // Exception should never occur as we are waiting when the queue is
              // full.
              FFDCFilter
                              .processException(
                                                e,
                                                "com.ibm.ws.sib.processor.impl.MessageProcessor.startNewSystemThread",
                                                "1:2758:1.445", this);
          }
  
          if (TraceComponent.isAnyTracingEnabled()
              && tc.isEntryEnabled())
              SibTr.exit(tc, "startNewSystemThread");
      }