#vulnerable code 
                                @Override
    public Result transfer(byte[] from, byte[] to, Na values, String password, String remark) {
        try {
            AssertUtil.canNotEmpty(from, "the from address can not be empty");
            AssertUtil.canNotEmpty(to, "the to address can not be empty");
            AssertUtil.canNotEmpty(values, "the amount can not be empty");

            if (values.isZero() || values.isLessThan(Na.ZERO)) {
                return Result.getFailed("amount error");
            }

            Result<Account> accountResult = accountService.getAccount(from);
            if (accountResult.isFailed()) {
                return accountResult;
            }
            Account account = accountResult.getData();

            if (accountService.isEncrypted(account).isSuccess()) {
                AssertUtil.canNotEmpty(password, "the password can not be empty");

                Result passwordResult = accountService.validPassword(account, password);
                if (passwordResult.isFailed()) {
                    return passwordResult;
                }
            }

            TransferTransaction tx = new TransferTransaction();
            if (StringUtils.isNotBlank(remark)) {
                try {
                    tx.setRemark(remark.getBytes(NulsConfig.DEFAULT_ENCODING));
                } catch (UnsupportedEncodingException e) {
                    e.printStackTrace();
                }
            }
            tx.setTime(TimeService.currentTimeMillis());
            CoinData coinData = new CoinData();
            Coin toCoin = new Coin(to, values);
            coinData.getTo().add(toCoin);

            CoinDataResult coinDataResult = getCoinData(from, values, tx.size() + P2PKHScriptSig.DEFAULT_SERIALIZE_LENGTH);
            if (!coinDataResult.isEnough()) {
                return Result.getFailed(LedgerErrorCode.BALANCE_NOT_ENOUGH);
            }
            coinData.setFrom(coinDataResult.getCoinList());
            if (coinDataResult.getChange() != null) {
                coinData.getTo().add(coinDataResult.getChange());
            }
            tx.setCoinData(coinData);

            tx.setHash(NulsDigestData.calcDigestData(tx.serialize()));
            P2PKHScriptSig sig = new P2PKHScriptSig();
            sig.setPublicKey(account.getPubKey());
            sig.setSignData(accountService.signData(tx.getHash().serialize(), account, password));
            tx.setScriptSig(sig.serialize());

            ValidateResult result1 = tx.verify();
            if (result1.isFailed()) {
                return result1;
            }
            result1 = this.ledgerService.verifyCoinData(tx, this.getAllUnconfirmedTransaction().getData());
            if (result1.isFailed()) {
                return result1;
            }

            Result saveResult = saveUnconfirmedTransaction(tx);
            if (saveResult.isFailed()) {
                return saveResult;
            }
            Result sendResult = this.transactionService.broadcastTx(tx);
            if (sendResult.isFailed()) {
                return sendResult;
            }
            return Result.getSuccess().setData(tx.getHash().getDigestHex());
        } catch (IOException e) {
            Log.error(e);
            return Result.getFailed(e.getMessage());
        } catch (NulsException e) {
            Log.error(e);
            return Result.getFailed(e.getErrorCode());
        }
    } 
                            #location 53 
                            #vulnerability type THREAD_SAFETY_VIOLATION
#fixed code
                                @Override
    public Result transfer(byte[] from, byte[] to, Na values, String password, String remark) {
        try {
            AssertUtil.canNotEmpty(from, "the from address can not be empty");
            AssertUtil.canNotEmpty(to, "the to address can not be empty");
            AssertUtil.canNotEmpty(values, "the amount can not be empty");

            if (values.isZero() || values.isLessThan(Na.ZERO)) {
                return Result.getFailed("amount error");
            }

            Result<Account> accountResult = accountService.getAccount(from);
            if (accountResult.isFailed()) {
                return accountResult;
            }
            Account account = accountResult.getData();

            if (accountService.isEncrypted(account).isSuccess()) {
                AssertUtil.canNotEmpty(password, "the password can not be empty");

                Result passwordResult = accountService.validPassword(account, password);
                if (passwordResult.isFailed()) {
                    return passwordResult;
                }
            }

            TransferTransaction tx = new TransferTransaction();
            if (StringUtils.isNotBlank(remark)) {
                try {
                    tx.setRemark(remark.getBytes(NulsConfig.DEFAULT_ENCODING));
                } catch (UnsupportedEncodingException e) {
                    e.printStackTrace();
                }
            }
            tx.setTime(TimeService.currentTimeMillis());
            CoinData coinData = new CoinData();
            Coin toCoin = new Coin(to, values);
            coinData.getTo().add(toCoin);

            CoinDataResult coinDataResult = getCoinData(from, values, tx.size() + P2PKHScriptSig.DEFAULT_SERIALIZE_LENGTH);
            if (!coinDataResult.isEnough()) {
                return Result.getFailed(LedgerErrorCode.BALANCE_NOT_ENOUGH);
            }
            coinData.setFrom(coinDataResult.getCoinList());
            if (coinDataResult.getChange() != null) {
                coinData.getTo().add(coinDataResult.getChange());
            }
            tx.setCoinData(coinData);

            tx.setHash(NulsDigestData.calcDigestData(tx.serialize()));
            P2PKHScriptSig sig = new P2PKHScriptSig();
            sig.setPublicKey(account.getPubKey());
            sig.setSignData(accountService.signData(tx.getHash().serialize(), account, password));
            tx.setScriptSig(sig.serialize());


            Result saveResult = saveUnconfirmedTransaction(tx);
            if (saveResult.isFailed()) {
                return saveResult;
            }
            Result sendResult = this.transactionService.broadcastTx(tx);
            if (sendResult.isFailed()) {
                return sendResult;
            }
            return Result.getSuccess().setData(tx.getHash().getDigestHex());
        } catch (IOException e) {
            Log.error(e);
            return Result.getFailed(e.getMessage());
        } catch (NulsException e) {
            Log.error(e);
            return Result.getFailed(e.getErrorCode());
        }
    }