diff -u b/core/lib/Drupal/Core/Plugin/Discovery/CacheDecorator.php b/core/lib/Drupal/Core/Plugin/Discovery/CacheDecorator.php
--- b/core/lib/Drupal/Core/Plugin/Discovery/CacheDecorator.php
+++ b/core/lib/Drupal/Core/Plugin/Discovery/CacheDecorator.php
@@ -8,6 +8,7 @@
 namespace Drupal\Core\Plugin\Discovery;
 
 use Drupal\Component\Plugin\Discovery\CachedDiscoveryInterface;
+use Drupal\Component\Plugin\Discovery\DiscoveryInterface;
 
 /**
  * Enables static and persistent caching of discovered plugin definitions.