Edited Issue: Support [ResponseType(typeof(void))] for actions that return an IHttpActionResult with no response content [1197]

Many of the actions on our new AccountController return IHttpActionResult with an empty 200 OK response. The Help page tries to display response formats for these actions and displays an error saying it can't generate sample responses. Can we support adding [ResponseType(typeof(void))] to these actions so that the Help page behaves as if the action just returned void?