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

Issue #1938916 by joelpittet, akalata, a-fro, duellj, InternetDevels, lauriii: Convert locale theme tables to table #type

Issue #2144413 by tstoeckler, YesCT, robertdbailey, webflo, Schnitzel, Wim Leers, kfritsche, Jose Reyero, Gábor Hojtsy, prodosh: Config translation does not support text elements with a format

Issue #2316561 by jmolivas | YesCT: Type hint hooks with interface: ConfigurableLanguageInterface instead of LanguageEntity/ConfigurableLanguage.

Issue #2341341 by YesCT, martin107, vijaycs85, fran seva: Change public 'name' property access on languages to getName() and add back setName().

Issue #2028109 by tim.plunkett, almaudoh, twistor, larowlan, slashrsm, Berdir, Arla, neclimdul, Cottser: Convert hook_stream_wrappers() to tagged services.

Issue #2340667 by YesCT, Pedro Lozano, alexpott, martin107: Protect Drupal\Core\Language\Language::id, and use getId().

Issue #2246675 by rpayanm, johnstorey, holly.ross.drupal | mgbellaire: Remove all unnecessary 'template' lines in hook_theme() declarations.

Issue #2070737 by herom, EllaTheHarpy, alexpott: Change values of LanguageInterface::DIRECTION_(LTR/RTL) to ('ltr'/'rtl').

Issue #2226207 by lauriii, mgbellaire, Cottser, m1r1k, Mark Carver, LinL, rachel_norfolk, rteijeiro, skwashd, davidhernandez, euphoric_mv: Make 'template' the default output option for hook_theme().

Issue #2277103 by tim.plunkett, pwolanin, Wim Leers, dawehner, hotpizzas: Switch Drupal::l() and LinkGenerator to expect a Url object.

Issue #2343651 by xjm, tim.plunkett, Wim Leers, dinarcon, dawehner: Remove most remaining l() calls.

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

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

Issue #2328411 by dawehner, geerlingguy, herom: Convert all permissions to yml files and permission callbacks.

Issue #1842362 by vijaycs85, Sutharsan, Berdir, ocsilalala, skipyT: Replace locale_project table and improve caching.

Issue #2271005 by martin107, YesCT, alimac, mrjmd: Rename Language module's LanguageInterface to ConfigurableLanguageInterface and Language to ConfigurableLanguage.

Issue #2307419 by Wim Leers: AssetCollectionOptimizerInterface should allow listing and deleting all aggregates (optimized collection assets).

Issue #1533250 by YesCT, fran seva, TravisCarden, xjm, sriharsha.uppuluri | NROTC_Webmaster: Many coding standards clean-ups in locale module.

Issue #1978926 by likin, YesCT, Pancho, kim.pepper, h3rj4n, tim.plunkett, disasm, Luxian, neetu morwani | vijaycs85: Convert locale_translation_status_form to a Controller.

Issue #2246665 by jaredsmith, martin107, YesCT, filijonka, tstoeckler: Typehint with Drupal\Core\Language\LanguageInterface instead Drupal\Core\Language\Language.

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

Issue #2183113 by jhodgdon, effulgentsia, tim.plunkett, herom, larowlan: Update hook_help signature to use route_name instead of path.

Issue #2240463 by robertdbailey, balagan, holly.ross.drupal: Fix text: languages are not "enabled/disabled" anymore, they are added/removed.

Issue #2208609 by sun, Jalandhar, damiankloip: Move Json utility class into Drupal\Component\Serialization.

Issue #2221695 by brantwynn, ianthomas_uk, grom358, ParisLiakos, Jalandhar: Remove uses of deprecated URL functions.

Issue #2089433 by ianthomas_uk, grom358, herom, thedavidmeister, visabhishek, longwave, Sweetchuck: Remove uses of deprecated XSS filter functions.