diff --git a/core/lib/Drupal/Core/Entity/Entity/EntityFormDisplay.php b/core/lib/Drupal/Core/Entity/Entity/EntityFormDisplay.php
index 60fa71d6af..cf800783e1 100644
--- a/core/lib/Drupal/Core/Entity/Entity/EntityFormDisplay.php
+++ b/core/lib/Drupal/Core/Entity/Entity/EntityFormDisplay.php
@@ -376,14 +376,16 @@ public function getPluginCollections() {
    * {@inheritdoc}
    */
   public function setLayoutId($layout_id, array $layout_settings = []) {
-    return $this->entityManager->setLayoutId($layout_id, $layout_settings);
+    // @todo Not clear the purpose.
+    return $this->setLayoutFromId($layout_id, $layout_settings);
   }
 
   /**
    * {@inheritdoc}
    */
-  public function ensureLayout($layout_id = 'layout_onecol') {
-    return $this->entityManager->ensureLayout($layout_id);
+  public function ensureLayout($default_layout_id = 'layout_onecol') {
+    // @todo Not clear the purpose.
+    return $this->layout_id = $default_layout_id;
   }
 
 }
diff --git a/core/lib/Drupal/Core/Entity/Entity/EntityViewDisplay.php b/core/lib/Drupal/Core/Entity/Entity/EntityViewDisplay.php
index 128c1a1139..5ce8d11aed 100644
--- a/core/lib/Drupal/Core/Entity/Entity/EntityViewDisplay.php
+++ b/core/lib/Drupal/Core/Entity/Entity/EntityViewDisplay.php
@@ -379,14 +379,16 @@ public function getPluginCollections() {
    * {@inheritdoc}
    */
   public function setLayoutId($layout_id, array $layout_settings = []) {
-    return $this->entityManager->setLayoutId($layout_id, $layout_settings);
+    // @todo Not clear the purpose.
+    return $this->setLayoutFromId($layout_id, $layout_settings);
   }
 
   /**
    * {@inheritdoc}
    */
-  public function ensureLayout($layout_id = 'layout_onecol') {
-    return $this->entityManager->ensureLayout($layout_id);
+  public function ensureLayout($default_layout_id = 'layout_onecol') {
+    // @todo Not clear the purpose.
+    return $this->layout_id = $default_layout_id;
   }
 
 }
diff --git a/core/lib/Drupal/Core/Entity/EntityDisplayBase.php b/core/lib/Drupal/Core/Entity/EntityDisplayBase.php
index ff59380ac8..da9260d2c2 100644
--- a/core/lib/Drupal/Core/Entity/EntityDisplayBase.php
+++ b/core/lib/Drupal/Core/Entity/EntityDisplayBase.php
@@ -186,7 +186,6 @@ public function __construct(array $values, $entity_type) {
   protected function init() {
     // Only populate defaults for "official" view modes and form modes.
     if ($this->mode !== static::CUSTOM_MODE) {
-      $default_region = $this->getDefaultRegion();
       // Fill in defaults for extra fields.
       $context = $this->displayContext == 'view' ? 'display' : $this->displayContext;
       $extra_fields = \Drupal::service('entity_field.manager')->getExtraFields($this->targetEntityType, $this->bundle);
@@ -635,6 +634,7 @@ public function setLayoutFromId($layout_id, array $layout_settings = []) {
     $original_layout_id = $this->getLayoutId();
     $this->layout_id = $layout_id;
     $this->getPluginCollection()->addInstanceID($layout_id, $layout_settings);
+    $this->layout_settings = $this->getPluginCollection()->getConfiguration();
 
     if ($original_layout_id !== $layout_id) {
       // @todo Devise a mechanism for mapping old regions to new ones in
diff --git a/core/lib/Drupal/Core/Layout/Annotation/Layout.php b/core/lib/Drupal/Core/Layout/Annotation/Layout.php
index 371c1af3c8..8aaff51d6b 100644
--- a/core/lib/Drupal/Core/Layout/Annotation/Layout.php
+++ b/core/lib/Drupal/Core/Layout/Annotation/Layout.php
@@ -40,7 +40,9 @@ class Layout extends Plugin {
   public $label;
 
   /**
-   * An optional description for advanced layouts.
+   * A description for advanced layouts.
+   *
+   * This property is optional and it does not need to be declared.
    *
    * Sometimes layouts are so complex that the name is insufficient to describe
    * a layout such that a visually impaired administrator could layout a page
@@ -71,7 +73,9 @@ class Layout extends Plugin {
    * hook_theme() and the module or theme registering this layout does not need
    * to do it.
    *
-   * @var string optional
+   * This property is optional and it does not need to be declared.
+   *
+   * @var string
    *
    * @see hook_theme()
    */
@@ -80,11 +84,13 @@ class Layout extends Plugin {
   /**
    * The theme hook used to render this layout.
    *
+   * This property is optional and it does not need to be declared.
+   *
    * If specified, it's assumed that the module or theme registering this layout
    * will also register the theme hook with hook_theme() itself. This is
    * mutually exclusive with 'template' - you can't specify both.
    *
-   * @var string optional
+   * @var string
    *
    * @see hook_theme()
    */
@@ -93,28 +99,36 @@ class Layout extends Plugin {
   /**
    * Path (relative to the module or theme) to resources like icon or template.
    *
-   * @var string optional
+   * This property is optional and it does not need to be declared.
+   *
+   * @var string
    */
   public $path;
 
   /**
    * The asset library.
    *
-   * @var string optional
+   * This property is optional and it does not need to be declared.
+   *
+   * @var string
    */
   public $library;
 
   /**
    * The path to the preview image (relative to the 'path' given).
    *
-   * @var string optional
+   * This property is optional and it does not need to be declared.
+   *
+   * @var string
    */
   public $icon;
 
   /**
    * The icon map.
    *
-   * @var string[][] optional
+   * This property is optional and it does not need to be declared.
+   *
+   * @var string[][]
    *
    * @see \Drupal\Core\Layout\Icon\IconBuilderInterface::build()
    */
diff --git a/core/modules/field_layout/tests/src/FunctionalJavascript/FieldLayoutTest.php b/core/modules/field_layout/tests/src/FunctionalJavascript/FieldLayoutTest.php
index 467114bc72..3d48c67058 100644
--- a/core/modules/field_layout/tests/src/FunctionalJavascript/FieldLayoutTest.php
+++ b/core/modules/field_layout/tests/src/FunctionalJavascript/FieldLayoutTest.php
@@ -18,7 +18,6 @@ class FieldLayoutTest extends WebDriverTestBase {
   protected static $modules = [
     'field_layout',
     'field_ui',
-    'field_layout_test',
     'layout_test',
   ];
 
diff --git a/core/modules/system/tests/modules/layout_test/layout_test.info.yml b/core/modules/system/tests/modules/layout_test/layout_test.info.yml
index 8492c1b8bc..fbce7043fa 100644
--- a/core/modules/system/tests/modules/layout_test/layout_test.info.yml
+++ b/core/modules/system/tests/modules/layout_test/layout_test.info.yml
@@ -4,4 +4,4 @@ description: 'Support module for testing layouts.'
 package: Testing
 version: VERSION
 dependencies:
-  - entity_test
+  - drupal:entity_test
diff --git a/core/modules/system/tests/modules/layout_test/src/Plugin/Layout/TestLayoutContentFooter.php b/core/modules/system/tests/modules/layout_test/src/Plugin/Layout/TestLayoutContentFooter.php
index c283c82d78..62ae00e472 100644
--- a/core/modules/system/tests/modules/layout_test/src/Plugin/Layout/TestLayoutContentFooter.php
+++ b/core/modules/system/tests/modules/layout_test/src/Plugin/Layout/TestLayoutContentFooter.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace Drupal\field_layout_test\Plugin\Layout;
+namespace Drupal\layout_test\Plugin\Layout;
 
 use Drupal\Core\Layout\LayoutDefault;
 
diff --git a/core/modules/system/tests/modules/layout_test/src/Plugin/Layout/TestLayoutMainFooter.php b/core/modules/system/tests/modules/layout_test/src/Plugin/Layout/TestLayoutMainFooter.php
index cfe95e1377..154aee60a8 100644
--- a/core/modules/system/tests/modules/layout_test/src/Plugin/Layout/TestLayoutMainFooter.php
+++ b/core/modules/system/tests/modules/layout_test/src/Plugin/Layout/TestLayoutMainFooter.php
@@ -1,6 +1,6 @@
 <?php
 
-namespace Drupal\field_layout_test\Plugin\Layout;
+namespace Drupal\layout_test\Plugin\Layout;
 
 use Drupal\Core\Layout\LayoutDefault;
 
diff --git a/core/tests/Drupal/KernelTests/Core/Entity/EntityViewDisplayTest.php b/core/tests/Drupal/KernelTests/Core/Entity/EntityViewDisplayTest.php
index e0eacdd61b..a954661b43 100644
--- a/core/tests/Drupal/KernelTests/Core/Entity/EntityViewDisplayTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Entity/EntityViewDisplayTest.php
@@ -1,14 +1,15 @@
 <?php
 
-namespace Drupal\Tests\field_layout\Kernel;
+namespace Drupal\KernelTests\Core\Entity;
 
+use Drupal\Core\Entity\Entity\EntityViewDisplay;
 use Drupal\KernelTests\KernelTestBase;
 
 /**
- * @coversDefaultClass \Drupal\field_layout\Entity\FieldLayoutEntityDisplayTrait
+ * @coversDefaultClass \Drupal\field_layout\Entity\FieldLayoutEntityDisplayTrait`
  * @group field_layout
  */
-class FieldLayoutEntityDisplayTest extends KernelTestBase {
+class EntityViewDisplayTest extends KernelTestBase {
 
   /**
    * {@inheritdoc}
@@ -17,7 +18,7 @@ class FieldLayoutEntityDisplayTest extends KernelTestBase {
     'layout_discovery',
     'field_layout',
     'entity_test',
-    'field_layout_test',
+    'layout_test',
     'system',
   ];
 
@@ -45,14 +46,6 @@ public function testPreSave() {
       'langcode' => 'en',
       'status' => TRUE,
       'dependencies' => [],
-      'third_party_settings' => [
-        'field_layout' => [
-          'id' => 'layout_onecol',
-          'settings' => [
-            'label' => '',
-          ],
-        ],
-      ],
       'id' => 'entity_test.entity_test.default',
       'targetEntityType' => 'entity_test',
       'bundle' => 'entity_test',
@@ -77,9 +70,8 @@ public function testPreSave() {
     // The dependencies have been updated.
     $expected['dependencies']['module'] = [
       'entity_test',
-      'field_layout',
-      'layout_discovery',
     ];
+    $expected['layout_settings']['label'] = '';
     // A third party setting is added by the entity_test module.
     $expected['third_party_settings']['entity_test'] = ['foo' => 'bar'];
     // The visible field is assigned the default region.
@@ -106,6 +98,8 @@ public function testPreSave() {
       'settings' => [],
       'third_party_settings' => [],
     ];
+    $expected['layout_id'] = 'test_layout_main_and_footer';
+    $expected['layout_settings'] = ['setting_1' => 'Default'];
     $this->assertEntityValues($expected, $entity_display->toArray());
 
     // After saving, the dependencies have been updated.
@@ -114,8 +108,7 @@ public function testPreSave() {
       'dependency_from_annotation',
       'dependency_from_calculateDependencies',
       'entity_test',
-      'field_layout',
-      'field_layout_test',
+      'layout_test',
     ];
     $this->assertEntityValues($expected, $entity_display->toArray());
 
@@ -124,7 +117,7 @@ public function testPreSave() {
     $entity_display->save();
 
     // The setting overrides the default value.
-    $expected['third_party_settings']['field_layout']['settings']['setting_1'] = 'foobar';
+    $expected['layout_settings']['setting_1'] = 'foobar';
     $this->assertEntityValues($expected, $entity_display->toArray());
 
     // Move a field to the non-default region.
@@ -145,7 +138,7 @@ public function testPreSave() {
     $expected['dependencies']['module'] = [
       'entity_test',
       'field_layout',
-      'field_layout_test',
+      'layout_test',
     ];
     // The layout has been updated.
     $expected['third_party_settings']['field_layout'] = [
diff --git a/core/tests/Drupal/Tests/Core/Entity/Display/EntityFormDisplayTest.php b/core/tests/Drupal/Tests/Core/Entity/Display/EntityFormDisplayTest.php
index 6dbda03708..ee08a129ea 100644
--- a/core/tests/Drupal/Tests/Core/Entity/Display/EntityFormDisplayTest.php
+++ b/core/tests/Drupal/Tests/Core/Entity/Display/EntityFormDisplayTest.php
@@ -40,7 +40,7 @@ class EntityFormDisplayTest extends UnitTestCase {
   /**
    * {@inheritdoc}
    */
-  protected function setUp() {
+  protected function setUp(): void {
     parent::setUp();
 
     $this->pluginDefinition = new LayoutDefinition([
@@ -171,7 +171,7 @@ public function testApplyLayout() {
           '#process' => ['\Drupal\Core\Render\Element\RenderElement::processGroup'],
           '#pre_render' => ['\Drupal\Core\Render\Element\RenderElement::preRenderGroup'],
         ],
-        '#settings' => [],
+        '#settings' => ['label' => ''],
         '#layout' => $this->pluginDefinition,
         '#theme' => 'layout__twocol',
         '#attached' => [
diff --git a/core/tests/Drupal/Tests/Core/Entity/Display/EntityViewDisplayTest.php b/core/tests/Drupal/Tests/Core/Entity/Display/EntityViewDisplayTest.php
index 5e9d3d7bdc..81f635ee01 100644
--- a/core/tests/Drupal/Tests/Core/Entity/Display/EntityViewDisplayTest.php
+++ b/core/tests/Drupal/Tests/Core/Entity/Display/EntityViewDisplayTest.php
@@ -39,7 +39,7 @@ class EntityViewDisplayTest extends UnitTestCase {
   /**
    * {@inheritdoc}
    */
-  protected function setUp() {
+  protected function setUp(): void  {
     parent::setUp();
 
     $this->pluginDefinition = new LayoutDefinition([
@@ -171,7 +171,7 @@ public function testApplyLayout() {
             '#markup' => 'Configurable',
           ],
         ],
-        '#settings' => [],
+        '#settings' => ['label' => ''],
         '#layout' => $this->pluginDefinition,
         '#theme' => 'layout__twocol',
         '#attached' => [
@@ -257,7 +257,7 @@ public function testGetFieldFromBuild($field_name, $expected_field_array) {
             '#markup' => 'Configurable',
           ],
         ],
-        '#settings' => [],
+        '#settings' => ['label' => ''],
         '#layout' => $this->pluginDefinition,
         '#theme' => 'layout__twocol',
         '#attached' => [
@@ -348,7 +348,7 @@ public function testSetFieldOnBuildUnknownField() {
       'entity_view_display'
     );
 
-    $this->setExpectedException(\InvalidArgumentException::class, 'The field "unknown" was not expected');
+    $this->expectException(\InvalidArgumentException::class);
     $build = [];
     $display->setFieldOnBuild('unknown', ['#markup' => 'Unknown'], $build);
   }