@Override
    public synchronized String getTransactionKey() {
        if (this.transactionKey == null) {
            this.transactionKey =
                    "XID:" + this.formatId + ":" + HexSupport.toHexFromBytes(this.globalTransactionId) + ":"
                            + HexSupport.toHexFromBytes(this.branchQualifier) + ":" + this.uniqueQualifier;
        }
        return this.transactionKey;
    }
Just for test

@param formatId
@param branchQualifier
@param globalTransactionId
metamorphosis-commons/src/main/java/com/taobao/metamorphosis/transaction/XATransactionId.java