Sending a message in form of a class?

Let’s say I have a MyClass contains 3 variable of strings. And instead of
var content = new Dictionary<string, string> {{"hello", "world"}}.ToJson(); I want it to be var content = new Dictionary<string, MyClass> {{"hello", myClass}}.ToJson();. But I don’t see any object parameter in IApiChannelMessage to be serialized from Json later. Is it possible to achieve something like this?

Related to Unity crashes when I tried the TinyJson from Nakama - #2 by aliakbarm534