Issue #2004336 by damiankloip: Default UUID key in ConfigEntityType.

core/includes/entity.inc

core/lib/Drupal/Core/Config/Entity/ConfigEntityBase.php

core/lib/Drupal/Core/Config/Entity/ConfigEntityType.php

..._block/lib/Drupal/custom_block/Entity/CustomBlockType.php

core/modules/block/lib/Drupal/block/Entity/Block.php

...es/breakpoint/lib/Drupal/breakpoint/Entity/Breakpoint.php

...eakpoint/lib/Drupal/breakpoint/Entity/BreakpointGroup.php

...les/config/lib/Drupal/config/Tests/ConfigImportUITest.php

...les/config/lib/Drupal/config/Tests/ConfigImporterTest.php

.../config_test/lib/Drupal/config_test/Entity/ConfigTest.php

core/modules/contact/lib/Drupal/contact/Entity/Category.php

core/modules/entity/lib/Drupal/entity/EntityDisplayBase.php

...odules/entity/lib/Drupal/entity/EntityDisplayModeBase.php

core/modules/field/lib/Drupal/field/Entity/FieldConfig.php

...les/field/lib/Drupal/field/Entity/FieldInstanceConfig.php

.../modules/filter/lib/Drupal/filter/Entity/FilterFormat.php

core/modules/image/lib/Drupal/image/Entity/ImageStyle.php

.../modules/language/lib/Drupal/language/Entity/Language.php

core/modules/migrate/lib/Drupal/migrate/Entity/Migration.php

core/modules/node/lib/Drupal/node/Entity/NodeType.php