Issue #3436468 by longwave, smustgrave, alexpott: AjaxResponseSubscriber should lazily instantiate AjaxResponseAttachmentsProcessor

Issue #3366287 by lauriii, catch, dmurphy1: [regression] Inserting media via the media library modal when paged redirects to the wrong destination

Issue #3328454 by xjm, Bhanu951, jidrone, smustgrave: Replace most strpos() !== FALSE or === FALSE with str_contains()

Issue #3232097 by daffie, longwave: [Symfony 6] Add "array" type hint to methods overriding Symfony\Component\EventDispatcher\EventSubscriberInterface::getSubscribedEvents()

Issue #3236284 by alexpott: Passing request headers to string functions causes deprecations in PHP 8.1

Issue #3094398 by martin107, alexpott, andypost, klausi: Update Symfony response and request events to new classes

Issue #2776975 by joelpittet, dawehner, tim.plunkett, xjm, pfrenssen: March 3, 2017: Convert core to array syntax coding standards for Drupal 8.3.x RC phase

Issue #2572777 by andypost, alexpott, attiks, andriyun: Fix 'Squiz.Strings.ConcatenationSpacing' coding standard

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

Issue #2554219 by nod_, larowlan, tim.plunkett, regilero, droplet, japerry, samuel.mortenson, Pere Orga, effulgentsia, benjy, Gábor Hojtsy, greggles, Wim Leers, David_Rothstein, pwolanin, neclimdul, EclipseGc, znerol: Port Cross-site Scripting - Ajax system fixes from SA-CORE-2015-003 to Drupal 8

Issue #2407195 by Wim Leers, Fabianx, joelpittet, lauriii, Crell: Move attachment processing to services and per-type response subclasses

Issue #2121713 by tim.plunkett, dawehner, rteijeiro, jiv_e: Move drupal_html_id() and drupal_html_class() to Drupal\Component\Utility.

Issue #2004086 by dawehner, pwolanin, katbailey, tim.plunkett, vijaycs85, fabpot: The Request service must be synthetic.