How can I build an Hedwig Adapter to use an embedded HTTP Server?

I would like to integrate Hedwig Chat application with a proprietary instant messaging server. The IM service supports calling an external HTTP server to pass the chat message via POST. I’ve looked at the example Hedwig adapters, but don’t find a good example that uses an embedded HTTP server for receiving chatbot messages.

Does anyone know of a possible example I can lean on to program the adapter?

I’ve gotten a skeleton adapter constructed, but I am stumbling on whether I should use Plug, Cauldron, or take the time to learn Cowboy. My need is take in a simple post and provide a response (body, status). Any suggestions?

Thanks for the advice ahead of time.