DialogFlow FulfillmentText doesn't appear in the chat Default Response

Question

I created a webhook for my agent, it works fine, I got a successful response from my webhook:

But I got no response in the test chat:

What I need to do to show it in the Default Response?

Answer 1

I was sending the keys with PascalCase, I needed to use camelCase. So I had to format the settings of the Json.

In Visual Studio (.NET Framework 4.5):

var jsonSerializer = new JsonSerializerSettings
        {
            ContractResolver = new CamelCasePropertyNamesContractResolver(),
            NullValueHandling = NullValueHandling.Ignore
        };

return Json(response, jsonSerializer);

Note: In .NET Core, camelCase is default.