Issue #3209723 by murilohp, daffie, longwave, andypost: [Symfony 6] Symfony\Component\HttpKernel\HttpKernelInterface::MASTER_REQUEST is deprecated, use ::MAIN_REQUEST instead

Issue #3232082 by daffie, longwave, catch: [Symfony 6] Add "Response" type hint to methods that implement the method Symfony\Component\HttpKernel\HttpKernelInterface::handle()

Issue #3195533 by daffie, longwave: [Symfony 6] The constant Symfony\Component\HttpFoundation\Request::HEADER_X_FORWARDED_ALL is deprecated

Issue #3104307 by Berdir, longwave, Gábor Hojtsy, Wim Leers, alexpott, andypost: Remove  BC layers in various Drupal\Core components

Issue #3030501 by alexpott, Gábor Hojtsy, Berdir: [Symfony 4] Drupal\Core\StackMiddleware\ReverseProxyMiddleware calls Symfony\Component\HttpFoundation\Request::setTrustedHeaderName() which does not exist

Issue #2927746 by alexpott, catch, slasher13, mpdonadio, martin107, RoSk0, jibran, larowlan, pounard, Mile23, Jo Fitzgerald, deviantintegral, pritish.kumar: Update Symfony components to 3.4.*

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

Issue #313145 by ghoti, t0xicCode, znerol, pwolanin, thedavidmeister, seanr, neclimdul, Damien Tournoud: Support X-Forwarded-* HTTP headers alternates

Issue #1392754 by tss, justAChris, jhodgdon: Comply with new documentation standards for @file for namespaced class files

Issue #2303673 by dawehner, damiankloip, effulgentsia, Fabianx: Implement stackphp; cleanup handlePageCache() and preHandle()