Instead of explicitly stating return respond().json(object); or return respond().xml(object); it should be possible to just state the object to be returned, and then base the response type on requested 'Accept' header.

This, of course, is not trivial, as we need to handle the possibility that the requested could be html.
Should the object somehow be translated into a reserved keyword for the template engine, like StringTemplate uses it?
Or should the keyword be based on the objects class name and thus possibly break the reusability of the template?

Setting the html issue aside, a proposed return signature could be: return respond(object); or return respond().accept(object); or return respond().asRequested(object);

If one after all still keeps the html issue in mind, the return signature could also be with an optional keyword specifier, like return respond().asRequested("person", object);