private async void When_client_sends_METHOD_URL_request(HttpMethod method, string url)
 {
     await _client.SendAsync(method, url);
 }
 private async void When_client_sends_METHOD_URL_request_with_headers_and_json_content(HttpMethod method, string url, [FormatCollection] Dictionary <string, string> headers, object content)
 {
     await _client.SendAsync(new HttpRequestMessage(method, url).WithJsonContent(content).WithHeaders(headers));
 }