Whenever HAL FORMS is supposed to be rendered, we now adapt the `Content-Type` header depending on whether affordances (and thus `_templates`) are present. If none can be found, we either adapt the header to either `application/hal+json` or even `application/json` depending on the `Accept` header arrangement given. If none match, we reject the request with `406 Not Acceptable`.
Had to reintroduce a dependency on Lombok to use @SneakyThrows as otherwise we cannot throw HttpMediaTypeNotAcceptableException from a ResponseBodyAdvice. A manual implementation of the pattern does not compile on Java 8 (at least on MacOS).
Fixes#2060.
1dae476040