Introduce composed annotations for @RequestMapping

[sbrannen]

This commit introduces the following common composed annotations for
@RequestMapping in Spring MVC and Spring MVC REST.

• @GetMapping
• @PostMapping
• @PutMapping
• @DeleteMapping
• @PatchMapping

Issue: SPR-13992

[sdeleuze]

👍

[rstoyanchev]

Looks good overall. I'm wondering if we shouldn't also drop produces on POST, PUT, and PATCH? Also drop both consumes and produces on DELETE? It's less common to produce on those methods to begin with plus those conditions are for disambiguation purposes. They are not always needed, and you still have consumes.

[sbrannen]

@rstoyanchev, thanks for the review!

Those are exactly the topics I wanted to discuss with you: produces vs. consumes.

It's a bit of a challenge getting it right and not being too restrictive.

Regarding produces for POST, PUT, and PATCH, some people actually return the new/updated resource in the body in order to avoid having to submit a followup GET based on the 'location' header. So I thought we would want to allow such use cases. The same holds true for DELETE, though perhaps that's not so common.

Regarding consumes for DELETE, I also pondered whether we should include that. I doubt many people would submit a body with a DELETE request, but then again... I just didn't want to be too restrictive.

Let's come to a consensus during the team call -- OK?