Issue #1807042 by tim.plunkett, effulgentsia: Rename entity storage/list/form/render controllers to handlers, part 1: organize existing annotation keys.
Issue #1849752 by effulgentsia, Berdir, jibran, neclimdul: Abstract non-Drupal-specific parts of AnnotatedClassDiscovery into a Drupal\Component base class.
Issue #293318 by alex_b, Berdir, rootatwc, Aron Novak, mustafau, akahn: Convert Aggregator feeds into entities.
