diff --git a/core/lib/Drupal/Component/Plugin/Factory/DefaultFactory.php b/core/lib/Drupal/Component/Plugin/Factory/DefaultFactory.php
index 6753135..2315a7f 100644
--- a/core/lib/Drupal/Component/Plugin/Factory/DefaultFactory.php
+++ b/core/lib/Drupal/Component/Plugin/Factory/DefaultFactory.php
@@ -8,7 +8,6 @@
 
 use Drupal\Component\Plugin\Discovery\DiscoveryInterface;
 use Drupal\Component\Plugin\Exception\PluginException;
-use Drupal\Component\Plugin\Derivative\DeriverInterface;
 
 /**
  * Default plugin factory.
diff --git a/core/lib/Drupal/Component/Plugin/PluginManagerBase.php b/core/lib/Drupal/Component/Plugin/PluginManagerBase.php
index b3f451b..201b207 100644
--- a/core/lib/Drupal/Component/Plugin/PluginManagerBase.php
+++ b/core/lib/Drupal/Component/Plugin/PluginManagerBase.php
@@ -8,8 +8,6 @@
 namespace Drupal\Component\Plugin;
 
 use Drupal\Component\Plugin\Discovery\DiscoveryTrait;
-use Drupal\Component\Plugin\Exception\PluginException;
-use Drupal\Component\Utility\String;
 
 /**
  * Base class for plugin managers.
diff --git a/core/lib/Drupal/Core/Mail/MailManager.php b/core/lib/Drupal/Core/Mail/MailManager.php
index 20ca520..decbeed 100644
--- a/core/lib/Drupal/Core/Mail/MailManager.php
+++ b/core/lib/Drupal/Core/Mail/MailManager.php
@@ -12,8 +12,6 @@
 use Drupal\Core\Cache\CacheBackendInterface;
 use Drupal\Core\Extension\ModuleHandlerInterface;
 use Drupal\Core\Config\ConfigFactoryInterface;
-use Drupal\Component\Utility\String;
-use Drupal\Component\Plugin\Exception\InvalidPluginDefinitionException;
 use Drupal\Core\StringTranslation\StringTranslationTrait;
 use Drupal\Core\StringTranslation\TranslationInterface;
 
diff --git a/core/modules/migrate_drupal/src/Plugin/MigratePluginManager.php b/core/modules/migrate_drupal/src/Plugin/MigratePluginManager.php
index 8af36d6..c93ff07 100644
--- a/core/modules/migrate_drupal/src/Plugin/MigratePluginManager.php
+++ b/core/modules/migrate_drupal/src/Plugin/MigratePluginManager.php
@@ -2,7 +2,7 @@
 
 /**
  * @file
- * Contains \Drupal\migrate\Plugin\MigratePluginManager.
+ * Contains \Drupal\migrate_drupal\Plugin\MigratePluginManager.
  */
 
 namespace Drupal\migrate_drupal\Plugin;