Issue #1871762 by eojthebrave, jibran, xjm: Add detailed documentation explaining the block system's architecture.

Issue #2248151 by tim.plunkett, xjm, alexpott: Configurable plugins can not control instance-specific config dependencies.

Issue #2158003 by Wim Leers, msonnabaum, effulgentsia, moshe weitzman: Remove Block Cache API in favor of blocks returning #cache with cache tags.

Issue #2195753 by tim.plunkett: Changes to config entities that use plugins are not propagated to the plugins.

Issue #2136403 by damiankloip: Block display_title option shows incorrect default value on block configuration form.

Issue #1956448 by benjy, tim.plunkett, ed.hollinghurst, YesCT: Use the block instance title on the block admin listing.

Issue #1951386 by benjy, theduke, andypost, tim.plunkett: Fixed Extend BlockPluginInterface::access to allow passing in an account.

Issue #2087231 by tim.plunkett, pwolanin: Add a PluginBase in the Core namespace with t() as a helper method.

Issue #2062573 by claudiu.cristea, tim.plunkett, Xano: Change notice: Add method defaultConfiguration() in ConfigurablePluginInterface.

Issue #1961542 by mtift, ParisLiakos: Added Drupal::transliteration() and replace calls to transliteration service with it.

Issue #2022897 by dawehner, sdboyer, tim.plunkett: Shift responsibility for creating unique config id/machine name off of (views) block plugins and onto BlockFormController.

Issue #1986802 by yched: Rename PluginInspectionInterface::getDefinition() to getPluginDefinition().

Issue #1927608 by EclipseGc, tim.plunkett, effulgentsia: Remove the tight coupling between Block Plugins and Block Entities.

Issue #1913618 by tim.plunkett, amateescu: Convert EntityFormControllerInterface to extend FormInterface.

Issue #1391694 by tim.plunkett, aspilicious, fago, pounard, plach, Crell, msonnabaum, tstoeckler: Use type-hinting for entity-parameters.

Issue #1969276 by effulgentsia, tim.plunkett, EclipseGc: Refactor block plugins to make room for a BlockBase::build() implementation.

Issue #1875260 by Gábor Hojtsy, xjm, brantwynn, EclipseGc, Bojhan: Fixed Make the block title required and allow it to be hidden.

Issue #1591806 by tim.plunkett, ryanissamson, jenlampton, Risse, psynaptic, Gábor Hojtsy, kmcculloch, pakmanlh, Rob Loach: Change block 'subject' so that it's called (admin_)label like everything else on the theme layer.

Issue #1479454 by Hugo Wetterberg, galooph, andypost, marcingy, heyrocker, larowlan, alexpott, tim.plunkett, fubhy, sun, dawehner: Convert user roles to configurables.

Revert "Issue #1479454 by Hugo Wetterberg, galooph, dawehner, andypost, marcingy, heyrocker, larowlan, alexpott, tim.plunkett, fubhy, sun: Change notice: Convert user roles to configurables."

Broke testbot. :(

This reverts commit 2ae15972.

Issue #1479454 by Hugo Wetterberg, galooph, dawehner, andypost, marcingy, heyrocker, larowlan, alexpott, tim.plunkett, fubhy, sun: Change notice: Convert user roles to configurables.

Issue #1871696 by tim.plunkett, xjm, sun, msonnabaum, EclipseGc: Convert block instances to configuration entities to resolve architectural issues.

Issue #1144716 by Dave Reid, sun: Allow vertical tabs elements to have #title and #description values.

Issue #1535868 by EclipseGc, tim.plunkett, xjm, Jody Lynn, sdboyer, naxoc, tizzo, effulgentsia, dawehner, disasm, beejeebus: Convert all blocks into plugins.