diff --git a/core/lib/Drupal/Component/Annotation/Plugin.php b/core/lib/Drupal/Component/Annotation/Plugin.php
index 8eaa626..c888092 100644
--- a/core/lib/Drupal/Component/Annotation/Plugin.php
+++ b/core/lib/Drupal/Component/Annotation/Plugin.php
@@ -39,10 +39,8 @@ class Plugin implements AnnotationInterface {
    */
   public function __construct($values) {
     $reflection = new \ReflectionClass($this);
-    // Only keep actual default values by ignoring NULL values.
-    $defaults = array_filter($reflection->getDefaultProperties(), function ($value) {
-      return $value !== NULL;
-    });
+    $defaults = $reflection->getDefaultProperties();
+    unset($defaults['definition']);
     $parsed_values = $this->parse($values);
     $this->definition = NestedArray::mergeDeep($defaults, $parsed_values);
   }