Issue #2576533 by alexpott, stefan.r, Wim Leers, dawehner, xjm, effulgentsia, catch: Rename SafeStringInterface to MarkupInterface and move related classes

Issue #2508884 by EclipseGc, tim.plunkett, dsnopek, japerry, sravya_12, swathin, Wim Leers, Fabianx, dawehner, yched: Make contexts immutable

Issue #2569069 by stefan.r, mr.baileys, alexpott, lauriii: Replace TranslationWrapper with TranslatableString and deprecate TranslationWrapper

Issue #2338081 by pwolanin, dawehner, effulgentsia, kgoel, vijaycs85, mpdonadio, chx, brandon.holtsclaw, alexpott, Gábor Hojtsy, Fabianx, catch, YesCT, JvE: Local Tasks, Actions, and Contextual links mark strings from derivatives (or alter hooks) as safe and translated

Issue #2354889 by larowlan, dawehner, lauriii, Berdir, catch, martin107, pfrenssen, EclipseGc, Fabianx, Wim Leers, dsnopek, jibran, tim.plunkett, andypost: Make block context faster by removing onBlock event and replace it with loading from a ContextManager

Issue #2375695 by Berdir, EclipseGc, tim.plunkett, Wim Leers, Fabianx, dawehner: Condition plugins should provide cache contexts AND cacheability metadata needs to be exposed

Issue #2513244 by Berdir, Wim Leers, EclipseGc, Fabianx: ContextHandler incorrectly checks required/optional contexts of plugins

Issue #1392754 by tss, justAChris, jhodgdon: Comply with new documentation standards for @file for namespaced class files

Issue #2350569 by webflo, alexpott, tim.plunkett: Allow external update of ConfigEntity properties that are associated with a PluginCollection

Issue #2467411 by klausi, fago: Context class does not use typed data trait correctly, leading to fatal errors

Issue #2443409 by Berdir: Add a way to entity manager to get fresh entity and field definitions without invalidating all caches

Issue #2423241 by Mile23: Merge ConfigurablePluginCollectionTest into DefaultLazyPluginCollectionTest

Issue #2409647 by zealfire: ContainerDerivativeDiscoveryDecoratorTest misses @covers and coversDefaultClass documentation

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

Issue #2378583 by tim.plunkett, EclipseGc: Core ContextAware Plugins have inconsistent ContextDefinition return docs

Issue #2378585 by EclipseGc, tim.plunkett: Multiple context requirements cannot be satisfied by a single value

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

Issue #2328111 by dawehner, martin107, neclimdul: Replace most instances of the DRUPAL_ROOT constant with the app.root container parameter.

Issue #2246647 by mpdonadio, cilefen, YesCT, tim.plunkett: Rename PluginBag to LazyPluginCollection.

Issue #2340123 by Wim Leers: Setting cache tags can be tricky: use strings instead of nested arrays to improve DX.

Issue #2333465 by marcvangend: Fixed Confusing exception message when Deriver plugin does not exist.

Issue #2318281 by tim.plunkett, dawehner | kim.pepper: Provide a standard way to check a plugin is an instance of the required interface.

Issue #2293205 by Berdir | tim.plunkett: Consider removing usage of DataDefinition in ContextHandler.

Issue #2270323 by sun, dawehner, neclimdul: Remove DRUPAL_ROOT constant redefinitions from unit tests.

Issue #697760 by sun: Replace getInfo() in tests with native phpDoc + annotations (following PHPUnit).

Issue #1875996 by Xano, tim.plunkett, neclimdul, Rajendar Reddy, Jalandhar: Reconsider naming conventions for derivative classes.

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

Issue #2278541 by tim.plunkett, kim.pepper, Bojhan, EclipseGc: Refactor block visibility to use condition plugins.