Issue #2851394 by GoZ, hgunicamp, oknate, jungle, wolffereast, tameeshb, mmatsoo, ridhimaabrol24, jofitz, swarad07, tanc, shaktik, dimaro, shashikant_chauhan, MerryHamster, quietone, nitesh624, martin_q, boaloysius, gaurav.kapoor, nitvirus, ankithashetty, Munavijayalakshmi, kostyashupenko, leolando.tan, amit.drupal, ravi.shankar, akashkrishnan01, Swapnil_Kotwal, Saviktor, mrinalini9, anmolgoyal74, Venkatesh Rajan.J, shimpy, lomasr, Dinesh18, shubham.prakash, mahtab_alam, markdorison, cilefen, longwave, bleen, xjm, alexpott, gmaltoni: Fix grammar 'a' to 'an' when necessary

Issue #2665992 by alexpott, klausi, heykarthikwithu, xjm, tstoeckler: @file is not required for classes, interfaces and traits

Issue #2406543 by alexpott: Remove ConfigFactory::setOverrideState and ConfigFactory::getOverrideState()

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

Issue #2346187 by Yaron Tal | tstoeckler: ConfigFactory and CongfigFactoryInterface should be @ingroup config_api.

Issue #2312135 by effulgentsia: Rename and protect ConfigFactory::getCacheKey(s)(); add a separate ConfigFactoryInterface::getCacheKeys().

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

Issue #2227187 by Mykhailo Gurei, Jalandhar, cs_shadow, mandar.harkare | Berdir: Stop refering to config storage as storage controller.

Issue #2219499 by Berdir, alexpott, Gábor Hojtsy, vijaycs85, swentel: Generalize language config override responsibility.

Issue #2215503 by Gábor Hojtsy, Wim Leers: Use services instead of event subscribers for config module overrides.

Issue #2191911 by Xano: Improve @param and @return variable types for \Drupal\Core\Config\ConfigFactoryInterface.