code: public void registerForEvents(SIMPMessage msg)
    {
      if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) SibTr.entry(tc, "registerForEvents", msg);
      msg.registerMessageEventListener(MessageEvents.PRE_PREPARE_TRANSACTION, this);  //183715.1
      // If COD reports required, register for the prePrepare callback
      if(msg.getReportCOD() != null && _destination instanceof BaseDestinationHandler)
        msg.registerMessageEventListener(MessageEvents.COD_CALLBACK, (BaseDestinationHandler) _destination);
      if (TraceComponent.isAnyTracingEnabled() && tc.isEntryEnabled()) SibTr.exit(tc, "registerForEvents");
    }
docs: Register for the pre prepare callback.