This commit introduces ….of(…) factory methods on all RepresentationModel types as well as Link. RepresentationModel.of(…) transparently creates a EntityModel or CollectionModel depending on the value handed into the method.
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.
