如何在Spring webflux中处理异常并返回正确的HTTP代码?

我有一个方法,它使用Mono.fromfuture(result)给出响应,并抛出状态为400的CustomException。 现在在我的服务类中,当我调用那个方法时,我抛出的错误和代码不会传播到我的客户机(邮递员)。只有信息是我看到的。

我得到以下格式:-

{
    "timestamp": "2019-02-01T11:13:32.748+0000",
    "path": "/some_url",
    "status": 500,
    "error": "Internal Server Error",
    "message": "Unable to fetch Response"
}

期望(我想要实现的目标):-

{
    "timestamp": "2019-02-01T11:13:32.748+0000",
    "path": "/some_url",
    "status": 400,                           // (my own status)
    "error": "INVALID_ARGUMENT",             // (my own error)
    "message": "Unable to fetch Response"
}

我的代码:-

public Mono<ResponseObject> fetchResponse(arg) {

   return Mono.just(somedata which will give exception)
      .flatMap(k -> callExternalService(k))
      .onErrorMap(e -> Mono.error(
            new BusinessException("Unable to fetch Response", e))

       */* e here is giving :-
        "code" : 400,
        "message" : "Request contains an invalid argument.",
        "status" : "INVALID_ARGUMENT" */*
}