public void HeaderKnownValuesGetSerializedToJson()
        {
            var message = new HttpResponseMessage();
            message.Content = new StringContent("Test");
            message.Headers.Add("h1", "value");
            message.Headers.Add("h2", "");
            message.Headers.Add("h3", new string[] { "value1", "value2" });

            var json = message.GetHeadersAsJson().ToString();

            var expectedJsonString = string.Format("{{{0}  \"h1\": \"value\",{0}  \"h2\": \"\",{0}  \"h3\": [{0}    \"value1\",{0}    \"value2\"{0}  ],{0}  \"Content-Type\": \"text/plain; charset=utf-8\"{0}}}",
                Environment.NewLine);
            Assert.Equal(expectedJsonString, json);
        }