Prefer dynamic content generation via static; the static content type established by the annotations
isn't very flexible and is not backwards compatible. This change set eliminates the static annotations
in favor of assessing the content type requested by the client and attempting to give it what it wants,
falling back to HTTP 204 (no content) if there's not a suitable match.
- Any client Accept header that matches application/json will get a "pong" JSON object.
- Any client Accept header that matches text/* will get a pong text string.
- Lack of an Accept header will get a pong text string.
- An Accept header for an unsupported type like image/png should yield an HTTP 204 response
xref D900
why the "\" here? this is likely causing the difference in the test.