Issue #2815829 by godotislate, tim.plunkett, smustgrave, alexpott, xjm, bircher, paulocs: Adding or editing a block through the UI saves the entity twice

Issue #2852557 by bircher, alexpott, longwave, nedjo, dww: Config export key order is not predictable, use config schema to order keys for maps

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 #2339151 by EclipseGc, tim.plunkett, Gábor Hojtsy, effulgentsia: Conditions / context system does not allow for multiple configurable contexts, eg. language types

Issue #2246647 by mpdonadio, cilefen, YesCT, tim.plunkett: Rename PluginBag to LazyPluginCollection.

Issue #2278541 by tim.plunkett, kim.pepper, Bojhan, EclipseGc: Refactor block visibility to use condition plugins.