Issue #3238942 by andypost, alexpott: \Drupal\Core\Routing\RedirectDestination::get() causes deprecation errors on PHP 8.1

Issue #2809789 by pwolanin, dawehner: UrlGenerator fails to urlencode aliases, incorrectly encodes "system" path

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

Issue #2455083 by dawehner, larowlan, klausi, David_Rothstein, hefox, tsphethean, dstol, DamienMcKenna, Pere Orga, benjy: Open redirect fixes from SA-CORE-2015-001 need to be ported to Drupal 8