Cleanups in Affordance API and implementations of hypermedia type (de)serializers. Added a lot more domain methods and types to Link, ResourceSupport etc. to be able to move a lot of representation building logic into those.
AffordanceModelFactory is not a Spring Plugin anymore as that functionality is not needed currently as we statically look up all factories via the SpringFactoriesLoader mechanism.
Redesigned LinkRelation to become a first class abstraction in the codebase. IanaLinkRelations is now a collection of constants. Link now keeps a LinkRelation instance around instead of a plain String.
Tweaked LinkDiscoverer API to return Optional and Links instead of nullable Link and List<Link>.
Tweaked API of CurieProvider to make use of the newly introduced HalLinkRelation based on the general LinkRelation.
Additional fixes for the Kotlin extension functions. Make Kotlin build setup compile with JDK 8. Removed Objects helper class in favor of Spring's already existing Assert and it's usage in ResourceAssemblerSupport.
The LinkDiscoverer interface is now a Plugin<MediaType> to allow selecting a discoverer per media type. We also provide a LinkDiscoverers wrapper around a PluginRegistry for easier injection.
Dropped DefaultLinkDiscoverer as the above mentioned changed prohibits the usage of a discoverer without a media type. Clients that previously used DefaultLinkDiscoverer should switch to JsonPathLinkDiscoverer with a custom JsonPath expression and media type.
@EnableHypermediaSupport now supports multiple HypermediaType values set to be able to set up support for multiple hypermedia formats. Admittedly, the only currently supported type is HAL but we prepare for the addition of other (e.g. Collection/JSON or the like). We changed the infrastructure setup taken care of by @EnableHypermediaSupport to not enrich all ObjectMapper instances with our HAL modules but explicitly register an ObjectMapper with the application context and then registering a custom MappingJackson(2)HttpMessageConverter with the HandlerAdapter instances present in the ApplicationContext. We skip the registration if an already registered MJ2HMC has an ObjectMapper already supporting the Spring HATEOAS mixins.
Removed some compiler warnings.
