public static RequestBuilder WithAuthentication(this RequestBuilder requestBuilder, string scheme, string parameter)
        {
            requestBuilder.OnRequest(r => r.Headers.Authorization = new AuthenticationHeaderValue(scheme, parameter));

            return(requestBuilder);
        }
        public static RequestBuilder WithHeader(this RequestBuilder requestBuilder, string name, params string[] values)
        {
            requestBuilder.OnRequest(r => r.Headers.Add(name, values));

            return(requestBuilder);
        }