我试图张贴一个附件到JIRA，但得到一个404 http错误。
我之前确实发表了一些评论，效果很好。
MY代码如下

string jsmlogin = "****";
            string jsmpass = "****";
   string _auth = string.Format("{0}:{1}", jsmlogin, jsmpass);
            string _enc = Convert.ToBase64String(Encoding.ASCII.GetBytes(_auth));
            string _cred = string.Format("{0} {1}", "Basic", _enc);
            string projKey = "DESK-1993";

            string postUrl = "https://******/rest/servicedeskapi/request/" + projKey + "/attachments";
            string jsmproxy = "http://********";
           
            
             var clientHandler = new HttpClientHandler();
            clientHandler.Proxy = new WebProxy(jsmproxy, true);
       
           HttpClient client = new HttpClient(clientHandler);

            client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Basic", _enc);
            client.DefaultRequestHeaders.Add("X-Atlassian-Token", "nocheck");
            client.DefaultRequestHeaders.Accept.Add(new System.Net.Http.Headers.MediaTypeWithQualityHeaderValue("application/json"));
            MultipartFormDataContent content = new MultipartFormDataContent();

           HttpContent fileContent = new ByteArrayContent(File.ReadAllBytes("z.txt.txt"));
           content.Add(fileContent, "file","z");
             var response = client.PostAsync(postUrl, content).Result;