Clean up code containing various patterns:
* Remove redundant `final`, `public`, and `static` declarations in interfaces and enums.
* Replace redundant `? extends Object` generic parameters with `?`.
* Convert collections to arrays using empty array instead of pre-sized one (modern JVM recommendation).
* Initialize collections using constructor call over `addAll`.
* Favor `addAll` over iterating and adding one-by-one.
* Take advantage of `Map.forEach` that was introduced with Java 8.
Introduced more caches for reusable value objects: UriTemplate, MethodParameters. Cache UriTemplate.toString() to avoid re-computation. Avoid recomputing the affordances if possible in WebHandler. Removed cache in AnnotatedParametersParameterAccessor as that one now transitively benefits from the one introduced in MethodParameters.
Related ticket: spring-projects/spring-framework#22730.
Significant rework of the nullability annotation introduction to not produce any warnings anymore. Added nullability annotations where still missing. Removed the ones that were added erroneously.
Tightened nullability contracts in a couple of places, most prominently LinkRelationProvider, that now uses a LookupContext as plugin delimiter so that implementations can selectively be looked up for item or collection link relation lookup.
Removed obsolete declaration of Findbugs dependency.
Introduced findRequiredLinkWithRel(…) methods on LinkDiscoverer to delegate to existing lookups but resolving the Optional into an IllegalArgumentException.
Fixed JsonPathLinkDiscoverer to return no links at all if a required path segment in the payload cannot be found which would have triggered a PathNotFoundException before.
Polished parameter names and JavaDoc. Moved base test cases into the right packages.
Changed the package structure to better reflect the different modules of the library. All client related code now lives in the client package, server related APIs in server with their respective WebMVC and WebFlux implementations in sub-packages.
Added migration script to allow users to easily migrate to the new structure and added reference documentation section on the migration.
Traversons built in defaulting to HAL HttpMessageConverters and LinkDiscoverer implementation now caused a cyclic relationship between the client and mediatype.hal packages. This has be fixed by looking up the defaults via a SpringFactories interface.
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.
Added application/hal+json;charset=UTF-8 to the media types enum. Traverson now configures all HAL flavors to be supported by the registered HAL-specific HttpMessageConverter.
Removed nullability of media type in JsonPathLinkDiscoverer. This requires subclasses that want to support all media types to explicitly configure MediaType.ALL.
Heavily inspired by the PR submitted by @drummond but very significantly rewritten.
We now avoid calling URI.toString() to early to prevent the need to re-parse it and thus accidentally cause a double-encoding.
Original pull request: #382.
Turned hop into a real value object by making it immutable. Added unit tests for Hop. use verbose concept names instead of abbreviations (e.g. parameters instead of params). Additional assertions and the documentation of such in JavaDoc. @since tag in new Hop class.
Original pull request: #350
Introduced a dedicated value object to abstract a Hop within a relation traversal. The Hop consists of a relation name and optional local template parameters that are applied to this particular hop when traversing it.
Changed the implementation of Traverson to work with Hops instead of plain rels and merges the global template parameters with the hop-local ones before expanding the templates found.
Original pull request: #350.
Introduced Traverson.getDefaultMessageConverters(…) to be able to obtain the list of default HttpMessageConverters depending on the given media types. Added overloads for varargs as well as a List for consistency.
Traverson now has an additional constructor taking a RestOperations instance which will be used instead of the default one. This allows more fine grained control over the HTTP request infrastructure used when performing link traversals.
Some internal polishing (moved from RestTemplate to RestOperations).
Original pull request: #203.
Traverson correctly applies headers when using JsonPath to evaluate GET result: accepts the media types it is configured for and preserves additional headers.
We're now consistently using Spring HATEOAS' UriTemplate instead of the Spring MVC one to be able to expand extended template parameters correctly.
Also the ObjectMapper used by Traverson to unmarshal JSON responses does not fail for unknown properties anymore.
Introduce Traverson as means to traverse hypermedia based APIs by providing a set of relation names to discover and follow to access the final representation. Traverson allows to specify a parameter map that will be used to potentially expand the URIs discovered.
We currently support LinkDiscoverer based relation discovery, which means that relations in HAL representations can be found by simply stating their names. Alternatively JSON path expressions can be used (starting with a $).
