如何使用ASP.Net MVC将原始文本转换为原始JSON格式？

Question

我在向API发送HTTP Request时遇到问题。

由于我发送的内容在Internal Server Error 500中，但应该在Text format中，因此我一直在使用API​​从下面的代码接收到JSON format。我也尝试过JsonConverter.SerializeObject来转换fileJson变量，但是它不起作用。

var client = new HttpClient();
                    var httpRequestMessage = new HttpRequestMessage
                    {
                        Method = HttpMethod.Post,
                        RequestUri = new Uri("https://some-url"),
                        Headers = {
                            { HttpRequestHeader.Authorization.ToString(), "Bearer " + token},
                            { HttpRequestHeader.Accept.ToString(), "application/json" },
                            { HttpRequestHeader.ContentType.ToString(), "application/json"},
                            { "client-id", "clientid"},
                            { "client-secret","clientsecret"},
                            { "partner-id","partnerid"},
                            { "X-Version", "1" }
                        },
                        Content = new StringContent(fileJson)
                    };

                    var response = client.SendAsync(httpRequestMessage).Result;

这是fileJson包含的字符串

{  
   "senderRefId":"TRANSFER0001",
   "tranRequestDate":"2018-08-10T08:40:45.897",
   "particulars":"particulars",
   "sender":{  
      "name":"name",
      "address":{  
         "line1":"line1",
         "line2":"line2",
         "city":"city",
         "province":"province",
         "zipCode":"zip",
         "country":"country"
      }
   }

我已经在Postman上对其进行了测试，当我的请求正文位于原始JSON format中时，它可以工作，而当它位于Text format中时，则出现错误。