#vulnerable code 
                                @Override
    public Result<Integer> saveUnconfirmedTransaction(Transaction tx) {
        return saveTransaction(tx, TransactionInfo.UNCONFIRMED);
    } 
                            #location 3 
                            #vulnerability type THREAD_SAFETY_VIOLATION
#fixed code
                                @Override
    public Result<Integer> saveUnconfirmedTransaction(Transaction tx) {
        saveLock.lock();
        try {
            ValidateResult result1 = tx.verify();
            if (result1.isFailed()) {
                return result1;
            }
            result1 = this.ledgerService.verifyCoinData(tx, this.getAllUnconfirmedTransaction().getData());
            if (result1.isFailed()) {
                return result1;
            }
            return saveTransaction(tx, TransactionInfo.UNCONFIRMED);
        } finally {
            saveLock.unlock();
        }
    }