Issue #2144879 by Wim Leers, yched: Brush up MetadataGeneratorInterface::generate(Field|Entity)(): use FieldItemListInterface + better naming.
Issue #2171759 by amateescu: Drupal\Core\Field\ConfigFieldItemList tries to use an inexistent FieldInstanceInterface.
Issue #2159595 by Gábor Hojtsy: CKEditor should pass paths to locale not URLs.