Issue #2349991 by fago, Xano, amateescu: Provide a trait for categorizing plugin managers and use it for conditions and actions

Issue #2339151 by EclipseGc, tim.plunkett, Gábor Hojtsy, effulgentsia: Conditions / context system does not allow for multiple configurable contexts, eg. language types

Issue #2038275 by tim.plunkett, mr.baileys, Sam Hermans: Convert hook_queue_info() to plugin system.

Issue #2299677 by er.pushpinderrana, gauravkhambhala | jhodgdon: Fix up annotation-related topics a bit.

Issue #2292889 by Berdir, tim.plunkett: Fixed ContextHandler does not expect ContextDefinitionInterface.

Issue #2281635 by fubhy, er.pushpinderrana, EclipseGc, blueminds, tim.plunkett: \Drupal\Core\Plugin\Context\Context should use a ContextDefinition class instead of arrays.

Issue #2216541 by jhodgdon, Gábor Hojtsy: Fill in topic/@defgroup docs for Internationalization overview.

Issue #2244447 by alexpott, sun, Berdir: Translation of low-level info/annotations leads to circular dependencies.

Issue #2079797 by ParisLiakos, Xano, amateescu, tim.plunkett: Provide a trait for $this->t() and $this->formatPlural().

Issue #2005716 by tim.plunkett, msonnabaum, dawehner, alexpott, effulgentsia: Promote EntityType to a domain object.

Issue #2077473 by dawehner, damiankloip, pwolanin: Replace local action plugin discovery with YamlDiscovery and handle routes with parameters.

Issue #2050919 by neclimdul, pwolanin, damiankloip, dawehner: Replace local task plugin discovery with YamlDiscovery.

Issue #2031473 by pwolanin, fubhy, dawehner, tim.plunkett: Convert menu local actions to plugins so that we can generate dynamic titles and paths.

Issue #1969970 by dawehner, jhodgdon, webchick, EclipseGc, tim.plunkett: Documentation for translatable plugin properties on annotations

Issue #1849752 by effulgentsia, Berdir, jibran, neclimdul: Abstract non-Drupal-specific parts of AnnotatedClassDiscovery into a Drupal\Component base class.

Issue #1849752 by effulgentsia, Berdir: Abstract non-Drupal-specific parts of AnnotatedClassDiscovery into a Drupal\Component base class.

- Patch #1683644 by chx, EclipseGc, tim.plunkett, aspilicious, xjm, dawehner, effulgentsia: use Annotations for plugin discovery.