restful put post_RequestMappingHandlerMapping

        public string sendPost(string postUrl, List<string> attachments, string postDataStr)
        {
            try
            {
                var client = new RestClient(postUrl);
                var request = new RestRequest(Method.POST);
                request.AddHeader("Cache-Control", "no-cache");
                request.AddHeader("content-type", "multipart/form-data");
                if (attachments != null)
                {
                    foreach (string attach in attachments)
                    {
                        string attachFile = attach;
                        if (File.Exists(attachFile))
                        {
                            request.AddFile("files", attach);
                        }
                    }
                }
                request.AddParameter("pdfjson", postDataStr);
                var response = client.Execute(request);
                var content = response.Content;
               return content;
            }
            catch (Exception ex) 
            { 
                throw ex; 
            }
        }