diff --git a/core/lib/Drupal/Core/Config/Action/Attribute/ActionMethod.php b/core/lib/Drupal/Core/Config/Action/Attribute/ActionMethod.php
index 0463871b179437541aae1e3cbd91a8bc7717d9fb..3960caa6221022ecec9bfb07e5d28e676520f5ce 100644
--- a/core/lib/Drupal/Core/Config/Action/Attribute/ActionMethod.php
+++ b/core/lib/Drupal/Core/Config/Action/Attribute/ActionMethod.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Config\Action\Attribute;
 
 // cspell:ignore inflector
diff --git a/core/lib/Drupal/Core/Config/Action/ConfigActionException.php b/core/lib/Drupal/Core/Config/Action/ConfigActionException.php
index 02e5220e340190230d955dda3f2027b67a34059f..3ad3579b260ba643ae7b03c2a1d68f776e69a4e8 100644
--- a/core/lib/Drupal/Core/Config/Action/ConfigActionException.php
+++ b/core/lib/Drupal/Core/Config/Action/ConfigActionException.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Config\Action;
 
 /**
diff --git a/core/lib/Drupal/Core/Config/Action/ConfigActionManager.php b/core/lib/Drupal/Core/Config/Action/ConfigActionManager.php
index 1dad628da36aa04b23acdc8b0e222bfe80fca2e6..cb030d6ba333c856958d5da5b9c9258ebd474d84 100644
--- a/core/lib/Drupal/Core/Config/Action/ConfigActionManager.php
+++ b/core/lib/Drupal/Core/Config/Action/ConfigActionManager.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Config\Action;
 
 use Drupal\Component\Plugin\PluginBase;
diff --git a/core/lib/Drupal/Core/Config/Action/ConfigActionPluginInterface.php b/core/lib/Drupal/Core/Config/Action/ConfigActionPluginInterface.php
index fb174b67e3c00dd111d4c47184258d61652bd3e6..6431ec959e8c135985f878e9c1c660c48eab9ee3 100644
--- a/core/lib/Drupal/Core/Config/Action/ConfigActionPluginInterface.php
+++ b/core/lib/Drupal/Core/Config/Action/ConfigActionPluginInterface.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Config\Action;
 
 /**
diff --git a/core/lib/Drupal/Core/Config/Action/DuplicateConfigActionIdException.php b/core/lib/Drupal/Core/Config/Action/DuplicateConfigActionIdException.php
index 9ba0ca8ff729667531bd54335633c226b3b97220..f1d69c57a311d88e8805206f947efe412e225ed4 100644
--- a/core/lib/Drupal/Core/Config/Action/DuplicateConfigActionIdException.php
+++ b/core/lib/Drupal/Core/Config/Action/DuplicateConfigActionIdException.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Config\Action;
 
 /**
diff --git a/core/lib/Drupal/Core/Config/Action/EntityMethodException.php b/core/lib/Drupal/Core/Config/Action/EntityMethodException.php
index 3a7b56442168df88161fa6f26582a4b2051ea765..3f4e71ec797ce8ec882cbe3feed5129fbb40db42 100644
--- a/core/lib/Drupal/Core/Config/Action/EntityMethodException.php
+++ b/core/lib/Drupal/Core/Config/Action/EntityMethodException.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Config\Action;
 
 /**
diff --git a/core/lib/Drupal/Core/Config/Action/Exists.php b/core/lib/Drupal/Core/Config/Action/Exists.php
index ec34b5740d0801c1aca3139d8f7a29186ade6fc6..39c8e472538e2f7e722390ad30d4f53fa9658f9d 100644
--- a/core/lib/Drupal/Core/Config/Action/Exists.php
+++ b/core/lib/Drupal/Core/Config/Action/Exists.php
@@ -1,6 +1,8 @@
 <?php
 // phpcs:ignoreFile
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Config\Action;
 
 use Drupal\Core\Config\Entity\ConfigEntityInterface;
diff --git a/core/lib/Drupal/Core/Config/Action/Plugin/ConfigAction/Deriver/EntityCreateDeriver.php b/core/lib/Drupal/Core/Config/Action/Plugin/ConfigAction/Deriver/EntityCreateDeriver.php
index 8f42f7ad9ac9df3d76a8a107c894f4700eeb6017..f029505b88bd7733f6d74f285597411e80d04a43 100644
--- a/core/lib/Drupal/Core/Config/Action/Plugin/ConfigAction/Deriver/EntityCreateDeriver.php
+++ b/core/lib/Drupal/Core/Config/Action/Plugin/ConfigAction/Deriver/EntityCreateDeriver.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Config\Action\Plugin\ConfigAction\Deriver;
 
 use Drupal\Component\Plugin\Derivative\DeriverBase;
diff --git a/core/lib/Drupal/Core/Config/Action/Plugin/ConfigAction/Deriver/EntityMethodDeriver.php b/core/lib/Drupal/Core/Config/Action/Plugin/ConfigAction/Deriver/EntityMethodDeriver.php
index fe99550c6cc886498c6f2a593ba0d4421c01905d..2577d8d7b923847be2d54a61abfd8fb4a16f8cf1 100644
--- a/core/lib/Drupal/Core/Config/Action/Plugin/ConfigAction/Deriver/EntityMethodDeriver.php
+++ b/core/lib/Drupal/Core/Config/Action/Plugin/ConfigAction/Deriver/EntityMethodDeriver.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Config\Action\Plugin\ConfigAction\Deriver;
 
 // cspell:ignore inflector
diff --git a/core/lib/Drupal/Core/Config/Action/Plugin/ConfigAction/EntityCreate.php b/core/lib/Drupal/Core/Config/Action/Plugin/ConfigAction/EntityCreate.php
index 1f20155140d80573246e6b2b3363d9101e07b8e3..ad33645b3ddf57b2f40ceb767c57d3d8cbc2ed10 100644
--- a/core/lib/Drupal/Core/Config/Action/Plugin/ConfigAction/EntityCreate.php
+++ b/core/lib/Drupal/Core/Config/Action/Plugin/ConfigAction/EntityCreate.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Config\Action\Plugin\ConfigAction;
 
 use Drupal\Core\Config\Action\Attribute\ConfigAction;
diff --git a/core/lib/Drupal/Core/Config/Action/Plugin/ConfigAction/EntityMethod.php b/core/lib/Drupal/Core/Config/Action/Plugin/ConfigAction/EntityMethod.php
index 0230c7a3ba9f806305bd895aececa9ad95355fc4..4e91f181cdeb0d1ca00a81cd28320c159d39cb11 100644
--- a/core/lib/Drupal/Core/Config/Action/Plugin/ConfigAction/EntityMethod.php
+++ b/core/lib/Drupal/Core/Config/Action/Plugin/ConfigAction/EntityMethod.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Config\Action\Plugin\ConfigAction;
 
 use Drupal\Core\Config\Action\Attribute\ConfigAction;
diff --git a/core/lib/Drupal/Core/Config/Action/Plugin/ConfigAction/SimpleConfigUpdate.php b/core/lib/Drupal/Core/Config/Action/Plugin/ConfigAction/SimpleConfigUpdate.php
index 0caf8662132cf4013acc9feca91bb991c9707fbe..d6485304cc0fa0d24ccbb450f428367e42906695 100644
--- a/core/lib/Drupal/Core/Config/Action/Plugin/ConfigAction/SimpleConfigUpdate.php
+++ b/core/lib/Drupal/Core/Config/Action/Plugin/ConfigAction/SimpleConfigUpdate.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Config\Action\Plugin\ConfigAction;
 
 use Drupal\Core\Config\Action\Attribute\ConfigAction;
diff --git a/core/lib/Drupal/Core/Config/Checkpoint/CheckpointExistsException.php b/core/lib/Drupal/Core/Config/Checkpoint/CheckpointExistsException.php
index 123ece5f533be4c9cd9b9cb23834a5fcb6c18cee..35a203b8be767c71a09b48a2c81eed2a2304cf4e 100644
--- a/core/lib/Drupal/Core/Config/Checkpoint/CheckpointExistsException.php
+++ b/core/lib/Drupal/Core/Config/Checkpoint/CheckpointExistsException.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Config\Checkpoint;
 
 /**
diff --git a/core/lib/Drupal/Core/Config/Checkpoint/CheckpointListInterface.php b/core/lib/Drupal/Core/Config/Checkpoint/CheckpointListInterface.php
index 5a2c569e2c8d768a5af5308ac2acd12b3f223694..dd3af0b07ddfff85e5685012035b8dae6475a608 100644
--- a/core/lib/Drupal/Core/Config/Checkpoint/CheckpointListInterface.php
+++ b/core/lib/Drupal/Core/Config/Checkpoint/CheckpointListInterface.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Config\Checkpoint;
 
 /**
diff --git a/core/lib/Drupal/Core/Config/Checkpoint/CheckpointStorageInterface.php b/core/lib/Drupal/Core/Config/Checkpoint/CheckpointStorageInterface.php
index 837033b022ad58b5dd68fe0aa755fe6fa55e08f9..fe476ac92757dc0bd756d04f3bbe9ef2a1028d2e 100644
--- a/core/lib/Drupal/Core/Config/Checkpoint/CheckpointStorageInterface.php
+++ b/core/lib/Drupal/Core/Config/Checkpoint/CheckpointStorageInterface.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Config\Checkpoint;
 
 use Drupal\Core\Config\StorageInterface;
diff --git a/core/lib/Drupal/Core/Config/Checkpoint/NoCheckpointsException.php b/core/lib/Drupal/Core/Config/Checkpoint/NoCheckpointsException.php
index 4ebda97426092bb447391c3fb84f288938455dc5..f0822b6210ca0f27c7618c953552d935e480fc61 100644
--- a/core/lib/Drupal/Core/Config/Checkpoint/NoCheckpointsException.php
+++ b/core/lib/Drupal/Core/Config/Checkpoint/NoCheckpointsException.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Config\Checkpoint;
 
 /**
diff --git a/core/lib/Drupal/Core/Config/Checkpoint/UnknownCheckpointException.php b/core/lib/Drupal/Core/Config/Checkpoint/UnknownCheckpointException.php
index 029585e30bd10ebefcd6a0f639c845e49432c3b4..0f99855822c421f6420b517208669d4e783032b3 100644
--- a/core/lib/Drupal/Core/Config/Checkpoint/UnknownCheckpointException.php
+++ b/core/lib/Drupal/Core/Config/Checkpoint/UnknownCheckpointException.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Config\Checkpoint;
 
 /**
diff --git a/core/lib/Drupal/Core/DefaultContent/Existing.php b/core/lib/Drupal/Core/DefaultContent/Existing.php
index a55674c21e0b7d1e89fb9781d1c66b9f5c4cf24e..75c5d8fff01279f42692f1023c969227c39db92d 100644
--- a/core/lib/Drupal/Core/DefaultContent/Existing.php
+++ b/core/lib/Drupal/Core/DefaultContent/Existing.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\DefaultContent;
 
 /**
diff --git a/core/lib/Drupal/Core/DefaultContent/ImportException.php b/core/lib/Drupal/Core/DefaultContent/ImportException.php
index ef358b9994bafc9944e7cfebc8762e05d1f10592..873b796bd2f85a1a6b76c9d1a52e9de07668754a 100644
--- a/core/lib/Drupal/Core/DefaultContent/ImportException.php
+++ b/core/lib/Drupal/Core/DefaultContent/ImportException.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\DefaultContent;
 
 /**
diff --git a/core/lib/Drupal/Core/Recipe/ConfigConfigurator.php b/core/lib/Drupal/Core/Recipe/ConfigConfigurator.php
index 3a5221ecb83fc53ce2b8f056248395c261ba83cb..2a379dab4f4d9ff4d33a33f06fd8cf8211dca145 100644
--- a/core/lib/Drupal/Core/Recipe/ConfigConfigurator.php
+++ b/core/lib/Drupal/Core/Recipe/ConfigConfigurator.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Recipe;
 
 use Drupal\Core\Config\FileStorage;
diff --git a/core/lib/Drupal/Core/Recipe/InstallConfigurator.php b/core/lib/Drupal/Core/Recipe/InstallConfigurator.php
index ce7996ee78963879bbad184e132765e367f934d4..abc51f5b269acc50797311a2e6d3e73c1ac8aeb0 100644
--- a/core/lib/Drupal/Core/Recipe/InstallConfigurator.php
+++ b/core/lib/Drupal/Core/Recipe/InstallConfigurator.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Recipe;
 
 use Drupal\Component\Assertion\Inspector;
diff --git a/core/lib/Drupal/Core/Recipe/Recipe.php b/core/lib/Drupal/Core/Recipe/Recipe.php
index 3c4595e04d3d4d8f49174a54b9d702a7c9ef4c7a..1baa8b9dec200628c150b5a0e326a5b6d2e5cef9 100644
--- a/core/lib/Drupal/Core/Recipe/Recipe.php
+++ b/core/lib/Drupal/Core/Recipe/Recipe.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Recipe;
 
 use Drupal\Core\DefaultContent\Finder;
diff --git a/core/lib/Drupal/Core/Recipe/RecipeAppliedEvent.php b/core/lib/Drupal/Core/Recipe/RecipeAppliedEvent.php
index 251139058cb8ae9564b2061b77ccb144d0517902..3e3078d23ca21b7d404651aab79aeff0fff203a6 100644
--- a/core/lib/Drupal/Core/Recipe/RecipeAppliedEvent.php
+++ b/core/lib/Drupal/Core/Recipe/RecipeAppliedEvent.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Recipe;
 
 use Symfony\Contracts\EventDispatcher\Event;
diff --git a/core/lib/Drupal/Core/Recipe/RecipeCommand.php b/core/lib/Drupal/Core/Recipe/RecipeCommand.php
index 31ad8dcfa80d60f6ec840a4b7d15e3188505194a..c370a450e855679877fe7a1719ed1e32a7f69ee7 100644
--- a/core/lib/Drupal/Core/Recipe/RecipeCommand.php
+++ b/core/lib/Drupal/Core/Recipe/RecipeCommand.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Recipe;
 
 use Drupal\Core\Config\Checkpoint\Checkpoint;
diff --git a/core/lib/Drupal/Core/Recipe/RecipeConfigInstaller.php b/core/lib/Drupal/Core/Recipe/RecipeConfigInstaller.php
index 2ee21703f2453d609e052c79fd69674c8dafce73..73c06151f74c49a8f8db19cdeb16321a7af37221 100644
--- a/core/lib/Drupal/Core/Recipe/RecipeConfigInstaller.php
+++ b/core/lib/Drupal/Core/Recipe/RecipeConfigInstaller.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Recipe;
 
 use Drupal\Core\Config\ConfigInstaller;
diff --git a/core/lib/Drupal/Core/Recipe/RecipeConfigStorageWrapper.php b/core/lib/Drupal/Core/Recipe/RecipeConfigStorageWrapper.php
index d2808d16ddc0516fbdf9c38498000217d37e8c0d..2f877833be17e040f0bba9d3ceae283c688c030b 100644
--- a/core/lib/Drupal/Core/Recipe/RecipeConfigStorageWrapper.php
+++ b/core/lib/Drupal/Core/Recipe/RecipeConfigStorageWrapper.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Recipe;
 
 use Drupal\Core\Config\NullStorage;
diff --git a/core/lib/Drupal/Core/Recipe/RecipeConfigurator.php b/core/lib/Drupal/Core/Recipe/RecipeConfigurator.php
index 851766fd5dda3f2f4de6e0b2d3a4ab2a98c4d518..3a238b329e70e520e995dd3cdaa0359846610f01 100644
--- a/core/lib/Drupal/Core/Recipe/RecipeConfigurator.php
+++ b/core/lib/Drupal/Core/Recipe/RecipeConfigurator.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Recipe;
 
 /**
diff --git a/core/lib/Drupal/Core/Recipe/RecipeDiscovery.php b/core/lib/Drupal/Core/Recipe/RecipeDiscovery.php
index 68310b3e73ee0a8e85a9f0120bee6f23f0b37f8f..cb6de7a781043fe6466d559e916d45fefcfedd2c 100644
--- a/core/lib/Drupal/Core/Recipe/RecipeDiscovery.php
+++ b/core/lib/Drupal/Core/Recipe/RecipeDiscovery.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Recipe;
 
 use Drupal\Component\Assertion\Inspector;
diff --git a/core/lib/Drupal/Core/Recipe/RecipeExtensionConfigStorage.php b/core/lib/Drupal/Core/Recipe/RecipeExtensionConfigStorage.php
index 4dfaf80d3e4f2cb5815ec85ff87f6e5df7812abd..389b256bda2b30583884f3bc4f31d2736350dc39 100644
--- a/core/lib/Drupal/Core/Recipe/RecipeExtensionConfigStorage.php
+++ b/core/lib/Drupal/Core/Recipe/RecipeExtensionConfigStorage.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Recipe;
 
 use Drupal\Core\Config\FileStorage;
diff --git a/core/lib/Drupal/Core/Recipe/RecipeFileException.php b/core/lib/Drupal/Core/Recipe/RecipeFileException.php
index bc7b9766fcb7475a029e47a7dcee2de61caf0b00..d45cc7ba494e5ed0b680555eb327c59a890f160e 100644
--- a/core/lib/Drupal/Core/Recipe/RecipeFileException.php
+++ b/core/lib/Drupal/Core/Recipe/RecipeFileException.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Recipe;
 
 use Symfony\Component\Validator\ConstraintViolationList;
diff --git a/core/lib/Drupal/Core/Recipe/RecipeMissingExtensionsException.php b/core/lib/Drupal/Core/Recipe/RecipeMissingExtensionsException.php
index ebef0229876e6c5f6ef03ddf135d52ad58e2085b..cdc2102196365b4bb6e8e6bbbfe299052c24b84e 100644
--- a/core/lib/Drupal/Core/Recipe/RecipeMissingExtensionsException.php
+++ b/core/lib/Drupal/Core/Recipe/RecipeMissingExtensionsException.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Recipe;
 
 use Drupal\Component\Assertion\Inspector;
diff --git a/core/lib/Drupal/Core/Recipe/RecipeOverrideConfigStorage.php b/core/lib/Drupal/Core/Recipe/RecipeOverrideConfigStorage.php
index 02cdca54c291cca9698f087d5e5d9c9747da28e3..9f97f71cd4d61872a2a701eeda0d1825c60f339a 100644
--- a/core/lib/Drupal/Core/Recipe/RecipeOverrideConfigStorage.php
+++ b/core/lib/Drupal/Core/Recipe/RecipeOverrideConfigStorage.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Recipe;
 
 use Drupal\Core\Config\StorageInterface;
diff --git a/core/lib/Drupal/Core/Recipe/RecipePreExistingConfigException.php b/core/lib/Drupal/Core/Recipe/RecipePreExistingConfigException.php
index cdd9eb0b1804d9c67671683881b830563298b5c5..39e5d4e2c7273c5c3dbded28d7bf9790e533ecae 100644
--- a/core/lib/Drupal/Core/Recipe/RecipePreExistingConfigException.php
+++ b/core/lib/Drupal/Core/Recipe/RecipePreExistingConfigException.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Recipe;
 
 /**
diff --git a/core/lib/Drupal/Core/Recipe/RecipeRunner.php b/core/lib/Drupal/Core/Recipe/RecipeRunner.php
index fe393db13cc98197ecccb4ab65ab416f4e28f8aa..5c16789cf0c1c15aff4b132e4dbd30f824841ba1 100644
--- a/core/lib/Drupal/Core/Recipe/RecipeRunner.php
+++ b/core/lib/Drupal/Core/Recipe/RecipeRunner.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Recipe;
 
 use Drupal\Core\Config\FileStorage;
diff --git a/core/lib/Drupal/Core/Recipe/UnknownRecipeException.php b/core/lib/Drupal/Core/Recipe/UnknownRecipeException.php
index 9351ba4dc63dc5350c31c15abc6c5f7b8699dcf6..8bfd61ea03d45434e090507def426d64578cf938 100644
--- a/core/lib/Drupal/Core/Recipe/UnknownRecipeException.php
+++ b/core/lib/Drupal/Core/Recipe/UnknownRecipeException.php
@@ -1,5 +1,7 @@
 <?php
 
+declare(strict_types=1);
+
 namespace Drupal\Core\Recipe;
 
 /**