docs: protected void internalRollback(Xid xid) throws XAException
     {
        if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) SibTr.entry(this, tc, "internalRollback", xid);
        
        try
        {
           CommsByteBuffer request = getCommsByteBuffer();
           request.putInt(getTransactionId());
           request.putXid(xid);
           if (fapLevel >= JFapChannelConstants.FAP_VERSION_5) {
              request.put((byte)(isMSResource ? 0x01 : 0x00));
           }           
           
           CommsByteBuffer reply = jfapExchange(request, 
                                                JFapChannelConstants.SEG_XAROLLBACK, 
                                                getLowestMessagePriority(), 
                                                true);
           try
           {
              reply.checkXACommandCompletionStatus(JFapChannelConstants.SEG_XAROLLBACK_R, getConversation());
           }
           finally
           {
              reply.release();
           }
        }
        catch (XAException xa)
        {
           // No FFDC Code needed
           // Simply re-throw...
           throw xa;
        }
        catch (Exception e)
        {
           FFDCFilter.processException(e, CLASS_NAME + ".internalRollback",
                                       CommsConstants.SIXARESOURCEPROXY_ROLLBACK_01, this);
           
           if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled()) SibTr.debug(this, tc, "Caught a comms problem:", e);
           throw new XAException(XAException.XAER_RMFAIL);
        }
        
        if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) SibTr.exit(this, tc, "internalRollback");
     }