Issue #2873696 by nvexler, wengerk, gido, Jo Fitzgerald, xjm: Add @internal to core classes, methods, properties to Form Classes

Issue #2901739 by andriyun, Jo Fitzgerald, mfernea, xjm: Fix 'Squiz.Arrays.ArrayDeclaration' coding standard

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 #1728804 by Berdir: Introduce (Content)EntityDeleteForm and children to handle entity deletions

Issue #2022875 by Berdir, alexpott, Xano, swentel, tim.plunkett, vladan.me: Resolve difference between submitForm(), submit(), and save() in EntityFormController.

Issue #2149197 by penyaskito, mikey_p, vijaycs85, herom: Replace format_interval with \Drupal::service('date')->formatInterval().

Issue #2226871 by tim.plunkett: ConfirmFormInterface::getCancelRoute() should always return Drupal\Core\Url.

Issue #1981368 by tim.plunkett, Crell, webchick: Convert all routes to 'module_name().foo_bar()' naming convention.

Issue #1963394 by tim.plunkett, jibran, effulgentsia: Fixed ConfirmFormBase::getCancelPath() should allow for a route.

Issue #1998140 by dawehner, ParisLiakos, tim.plunkett: Remove backward compatible ControllerInterface.

Issue #1946454 by andypost, kim.pepper, tim.plunkett, ParisLiakos: Convert all confirm_form() in system.module and system.admin.inc to the new form interface and convert route.