docs: public String getTransactionId() throws SIMPException
    {
      if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
        SibTr.entry(tc, "getTransactionId");
  
      assertValidControllable();
  
      String id = null;
      PersistentTranId pTranId = msgItem.getTransactionId();
      if (pTranId != null)
      {
        id = pTranId.toTMString();
      }
  
      if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled())
        SibTr.exit(tc, "getTransactionId", id);
      return id;
    }