Issue #956186 by catch, dpolant, SteffenR, yhahn, lauriii, nod_, sokrplare, rwaery.11, Supreetam09, effulgentsia, geek-merlin: Allow AJAX to use GET requests

Issue #3304285 by longwave, Spokje, bbrala, ravi.shankar, quietone, phenaproxima: Remove Seven from core

Issue #3304256 by longwave, Spokje, dww, lauriii, catch, quietone, mherchel: Remove Bartik from Drupal core

Issue #3254250 by Spokje, longwave, catch, daffie: [Symfony 6] Retrieving a non-string value from "Symfony\Component\HttpFoundation\InputBag::get()" is deprecated

Revert "Issue #3162016 by longwave, andypost, Hardik_Patel_12, catch, alexpott, daffie, Kristen Pol: [Symfony 6] Retrieving a non-string value from "Symfony\Component\HttpFoundation\InputBag::get()" is deprecated"

This reverts commit 8b8fc1ef.

Issue #3162016 by longwave, andypost, Hardik_Patel_12, catch, alexpott, daffie, Kristen Pol: [Symfony 6] Retrieving a non-string value from "Symfony\Component\HttpFoundation\InputBag::get()" is deprecated

Issue #2745953 by dawehner, tim.plunkett, Wim Leers: AjaxBasePageNegotiator should not require _theme: ajax_base_page to be specified

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

Issue #2502785 by dawehner, effulgentsia, tim.plunkett, amateescu, Fabianx, Wim Leers, catch, dsnopek, EclipseGc, yched, Berdir, larowlan, mondrake, olli: Remove support for $form_state->setCached() for GET requests

Issue #2238217 by effulgentsia, neclimdul, martin107, tim.plunkett, cweagans, kim.pepper, xjm: Introduce a RouteMatch class.

Issue #1954892 by dawehner, David_Rothstein, tim.plunkett: Replace 'theme callback' and hook_custom_theme() with a clean theme negotiation system.

Revert "Issue #1954892 by dawehner, tim.plunkett, David_Rothstein, effulgentsia: Replace 'theme callback' and hook_custom_theme() with a clean theme negotiation system."

This reverts commit fc04601c.

Issue #1954892 by dawehner, tim.plunkett, David_Rothstein, effulgentsia: Replace 'theme callback' and hook_custom_theme() with a clean theme negotiation system.