Issue #2453341 by Wim Leers: Contact forms don't have necessary cache contexts & tags; flood control should work on validate, not on view

Issue #2444231 by Wim Leers, nlisgo: Fix CacheableInterface so it makes sense (was: "Make Config objects & Entities implement CacheableInterface + add BubbleableMetadata::createFromCacheableObject()")

Issue #2459971 by Gábor Hojtsy: The langcode key on configuration files is not explicit in configuration schema

Issue #2457887 by prateekMehta, stefan.r, rpayanm, alexpott: Use Utility\SafeMarkup class instead of Utility\String for placeholder(), checkPlain(),format() functions

Issue #2428703 by Wim Leers: Add a 'user.permissions' cache context (was: "Should cache contexts be able to associate a cache tag?")

Issue #2090115 by alexpott, xjm: Don't install a module when its default configuration has unmet dependencies

Issue #2407765 by Wim Leers, borisson_: Wherever simple config is used to render output to end user, associate their cache tags

Issue #2404603 by mpdonadio, dawehner, larowlan, RavindraSingh: Add proper support for Url objects in FieldPluginBase::renderAsLink(), so we can remove EntityInterface::getSystemPath()

Issue #2394883 by Gábor Hojtsy, plach, jhodgdon: Language setup for entity and field based rendering in views is independent, confusing UI, lacking test coverage

Issue #2306407 by lauriii, penyaskito, mortendk, pakmanlh, Wim Leers, ypogue: Remove breadcrumb from page template

Issue #1728804 by Berdir: Introduce (Content)EntityDeleteForm and children to handle entity deletions

Issue #2225597 by tibbsa, larowlan, akozma: contact.module allows you to send emails to users with no email address - producing an error

Issue #2225427 by ianthomas_uk, martin107, JeroenT, LoMo: Remove remaining uses of deprecated language functions (mostly in object oriented code)

Issue #2392319 by alexpott, effulgentsia: Config objects (but not config entities) should by default be immutable

Issue #2040135 by Wim Leers, Berdir: Caches dependent on simple config are only invalidated on form submissions

Issue #2281645 by dawehner, andypost: Make entity annotations use link templates instead of route names

Issue #2395395 by alexpott, effulgentsia, Gábor Hojtsy: TestBase lacks a config method to be used consistently in tests

Issue #2230637 by plach, fran seva, yched, swentel: Create a Language field widget and the related formatter

Issue #1963340 by amateescu, dags, andypost, agentrickard, mgifford, yoroy, pguillard, jibran, YesCT, xjm, LewisNyman, swentel, Hydra, yched, tim.plunkett, rteijeiro, ainz, Xano, Bojhan, Berdir: Change field UI so that adding a field is a separate task

Issue #2349553 by dawehner, pfrenssen, damiankloip: Store entity field information in the views data

Issue #2183983 by Gábor Hojtsy, vijaycs85, Berdir, Wim Leers, webflo, alexpott: Find hidden configuration schema issues

Issue #2355909 by penyaskito, alexpott, Gábor Hojtsy, DuaelFr: language.settings config is not scalable

Issue #2383573 by tibbsa: Clean-up Contact module Test members - ensure property definition and use of camelCase naming convention

Issue #2365965 by er.pushpinderrana, larowlan, Cristian.Andrei, gaurav.pahuja: Various tests still have getInfo method

Issue #2379683 by Gábor Hojtsy: Fix configuration schema issues in contact (indirectly user and system) modules