Issue #2083811 by yched, plach: Remove langcode nesting for fields in entity structures.

core/lib/Drupal/Core/Entity/EntityFormController.php

core/lib/Drupal/Core/Entity/EntityFormControllerNG.php

...egator/lib/Drupal/aggregator/Tests/AggregatorTestBase.php

...lib/Drupal/custom_block/Tests/CustomBlockCreationTest.php

...ck/lib/Drupal/custom_block/Tests/CustomBlockFieldTest.php

...ock/lib/Drupal/custom_block/Tests/CustomBlockListTest.php

...stom_block/lib/Drupal/custom_block/Tests/PageEditTest.php

core/modules/book/lib/Drupal/book/Tests/BookTest.php

...keditor/lib/Drupal/ckeditor/Tests/CKEditorLoadingTest.php

...comment/lib/Drupal/comment/Tests/CommentAnonymousTest.php

...es/comment/lib/Drupal/comment/Tests/CommentFieldsTest.php

...comment/lib/Drupal/comment/Tests/CommentInterfaceTest.php

.../comment/lib/Drupal/comment/Tests/CommentLanguageTest.php

...s/comment/lib/Drupal/comment/Tests/CommentPreviewTest.php

...ules/comment/lib/Drupal/comment/Tests/CommentTestBase.php

.../contact/lib/Drupal/contact/Tests/ContactSitewideTest.php

...al/content_translation/Tests/ContentTranslationUITest.php

.../datetime/lib/Drupal/datetime/Tests/DatetimeFieldTest.php

core/modules/dblog/lib/Drupal/dblog/Tests/DbLogTest.php

core/modules/edit/lib/Drupal/edit/Form/EditFieldForm.php