累加List中的某一个值

        //查询账户余额信息
        List<AccountBalance> accountBalance = accountBalanceRepository.findByCustomerId(contractBaseInfo.getCustomerId());
        //账户总额
        BigDecimal rental = accountBalance.stream().map(AccountBalance::getBalance).reduce(BigDecimal.ZERO, BigDecimal::add).setScale(4, BigDecimal.ROUND_HALF_UP);