public async Task UploadSessionFileWithHttpMessagesAsync()

in ValidateSetup/src/ValidateSetup/MRSServer.cs [3450:3559]
100 lines of code
17 McCabe index (conditional complexity)

        public async Task<HttpOperationResponse> UploadSessionFileWithHttpMessagesAsync(string id, Stream file, Dictionary<string, List<string>> customHeaders = null, CancellationToken cancellationToken = default(CancellationToken))
        {
            if (id == null)
            {
                throw new ValidationException(ValidationRules.CannotBeNull, "id");
            }
            if (file == null)
            {
                throw new ValidationException(ValidationRules.CannotBeNull, "file");
            }
            // Tracing
            bool _shouldTrace = ServiceClientTracing.IsEnabled;
            string _invocationId = null;
            if (_shouldTrace)
            {
                _invocationId = ServiceClientTracing.NextInvocationId.ToString();
                Dictionary<string, object> tracingParameters = new Dictionary<string, object>();
                tracingParameters.Add("id", id);
                tracingParameters.Add("file", file);
                tracingParameters.Add("cancellationToken", cancellationToken);
                ServiceClientTracing.Enter(_invocationId, this, "UploadSessionFile", tracingParameters);
            }
            // Construct URL
            var _baseUrl = BaseUri.AbsoluteUri;
            var _url = new System.Uri(new System.Uri(_baseUrl + (_baseUrl.EndsWith("/") ? "" : "/")), "sessions/{id}/files").ToString();
            _url = _url.Replace("{id}", System.Uri.EscapeDataString(id));
            // Create HTTP transport objects
            var _httpRequest = new HttpRequestMessage();
            HttpResponseMessage _httpResponse = null;
            _httpRequest.Method = new HttpMethod("POST");
            _httpRequest.RequestUri = new System.Uri(_url);
            // Set Headers


            if (customHeaders != null)
            {
                foreach(var _header in customHeaders)
                {
                    if (_httpRequest.Headers.Contains(_header.Key))
                    {
                        _httpRequest.Headers.Remove(_header.Key);
                    }
                    _httpRequest.Headers.TryAddWithoutValidation(_header.Key, _header.Value);
                }
            }

            // Serialize Request
            string _requestContent = null;
            MultipartFormDataContent _multiPartContent = new MultipartFormDataContent();
            if (file != null)
            {
                 StreamContent _file = new StreamContent(file);
                _file.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");
                FileStream _fileAsFileStream = file as FileStream;
                if (_fileAsFileStream != null)
                {
                    ContentDispositionHeaderValue _contentDispositionHeaderValue = new ContentDispositionHeaderValue("form-data");
                    _contentDispositionHeaderValue.Name = "file";
                    _contentDispositionHeaderValue.FileName = _fileAsFileStream.Name;
                    _file.Headers.ContentDisposition = _contentDispositionHeaderValue;
                }
                _multiPartContent.Add(_file, "file");
            }
            _httpRequest.Content = _multiPartContent;
            // Send Request
            if (_shouldTrace)
            {
                ServiceClientTracing.SendRequest(_invocationId, _httpRequest);
            }
            cancellationToken.ThrowIfCancellationRequested();
            _httpResponse = await HttpClient.SendAsync(_httpRequest, cancellationToken).ConfigureAwait(false);
            if (_shouldTrace)
            {
                ServiceClientTracing.ReceiveResponse(_invocationId, _httpResponse);
            }
            HttpStatusCode _statusCode = _httpResponse.StatusCode;
            cancellationToken.ThrowIfCancellationRequested();
            string _responseContent = null;
            if ((int)_statusCode != 201)
            {
                var ex = new HttpOperationException(string.Format("Operation returned an invalid status code '{0}'", _statusCode));
                if (_httpResponse.Content != null) {
                    _responseContent = await _httpResponse.Content.ReadAsStringAsync().ConfigureAwait(false);
                }
                else {
                    _responseContent = string.Empty;
                }
                ex.Request = new HttpRequestMessageWrapper(_httpRequest, _requestContent);
                ex.Response = new HttpResponseMessageWrapper(_httpResponse, _responseContent);
                if (_shouldTrace)
                {
                    ServiceClientTracing.Error(_invocationId, ex);
                }
                _httpRequest.Dispose();
                if (_httpResponse != null)
                {
                    _httpResponse.Dispose();
                }
                throw ex;
            }
            // Create Result
            var _result = new HttpOperationResponse();
            _result.Request = _httpRequest;
            _result.Response = _httpResponse;
            if (_shouldTrace)
            {
                ServiceClientTracing.Exit(_invocationId, _result);
            }
            return _result;
        }