字段“值”上的对象“ currencyConversion”中的字段错误。类型不匹配

Question

我正在Spring Boot上的一个项目上工作，需要调用第三方API并从中获取数据。该应用程序涉及货币兑换。在执行货币转换时，出现错误。

Field error in object 'currencyConversion' on field 'value': rejected value [{10.0}]; codes [typeMismatch.currencyConversion.value,typeMismatch.value,typeMismatch.java.lang.Double,typeMismatch]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [currencyConversion.value,value]; arguments []; default message [value]]; default message [Failed to convert property value of type 'java.lang.String' to required type 'java.lang.Double' for property 'value'; nested exception is java.lang.NumberFormatException: For input string: "{10.0}"]]

CurrencyConversion.java

public class CurrencyConversion {

    private String to;
    private String from;
    private Double value;
    //Getters and Setters

服务等级

public Optional<Double> convert(CurrencyConversion currencyConversion) {

        Optional<Currency> toOptional = 
                this.currencyRepository.findById(currencyConversion.getTo().toUpperCase());
        Optional<Currency> fromOptional = 
                this.currencyRepository.findById(currencyConversion.getFrom().toUpperCase());

        if(toOptional.isPresent() && fromOptional.isPresent()) {
            if(currencyConversion.getValue() < 0) {
                return Optional.empty();
            }

            Currency to = toOptional.get();
            Currency from = fromOptional.get();
            Double toValue = to.getValues();
            Double fromValue = from.getValues();

            Double result = toValue * currencyConversion.getValue() / fromValue;

            return Optional.of(result);

        }
        return Optional.empty();
    }

控制器类

    @RequestMapping(value = "/convert/from{from}/to{to}/value{value}", produces = { "application/json" }, method = RequestMethod.POST)
    public ResponseEntity<Double> convertCurrencies(CurrencyConversion currencyConversion){
        Optional<Double> resultOptional = this.currencyService.convert(currencyConversion);
        if(resultOptional.isPresent()) {
            return new ResponseEntity<>(resultOptional.get(), HttpStatus.OK);
        }

        return new ResponseEntity<>(HttpStatus.BAD_REQUEST);
    }

我缺少什么，导致发生错误？