Problem

Reflect Message does not appear to send a message back to the client.

Resolution

Reflect Message has a confusing name and has never sent messages anywhere in any version. The only thing Reflect Message actually does is to modify http.response.info and http.response.code so you can send back 200 OK or 400 Bad Request.

What actually results in a message being sent back to the client is finishing the last filter in a policy. At that point, the API Gateway uses the contents of http.headers, http.response.info, http.response.code and content.body to create the reply that is actually sent to the client.