public Xid startTx(Xid xid) throws XAException
protected Xid startTx(Xid xid) throws XAException
   public Xid startTx(Xid xid) throws XAException   {      if (trace) { log.trace("starting " + xid); }      TxState state = getTx(xid);      if (state != null)      {         log.error("Transaction already exists with xid " + xid);         throw new XAException(XAException.XAER_DUPID);      }      transactions.put(xid, new TxState());      return xid;   }