Issue #2935256 by Jo Fitzgerald, voleger, kim.pepper, ibustos, Yogesh Pawar, catch, jibran: Remove all usages of drupal_get_message and drupal_set_message in modules

Issue #2873696 by nvexler, wengerk, gido, Jo Fitzgerald, xjm: Add @internal to core classes, methods, properties to Form 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 #2665992 by alexpott, klausi, heykarthikwithu, xjm, tstoeckler: @file is not required for classes, interfaces and traits

Issue #2560641 by alexpott, lauriii, Xano, borisson_, ianthomas_uk, olli: Remove all usages SafeMarkup::checkPlain() from render arrays

Revert "Issue #2560641 by alexpott, lauriii, Xano, borisson_, ianthomas_uk: Remove all usages SafeMarkup::checkPlain() from render arrays"

This reverts commit 31007609.

Issue #2560641 by alexpott, lauriii, Xano, borisson_, ianthomas_uk: Remove all usages SafeMarkup::checkPlain() from render arrays

Issue #2457887 by prateekMehta, stefan.r, rpayanm, alexpott: Use Utility\SafeMarkup class instead of Utility\String for placeholder(), checkPlain(),format() functions

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

Issue #1913084 by tim.plunkett: Introduce a Form interface for building, validating, and submitting forms.

Issue #1913084 by tim.plunkett: Introduce a Form interface for building, validating, and submitting forms.