diff --git a/core/lib/Drupal/Component/Plugin/Definition/PluginDefinitionInterface.php b/core/lib/Drupal/Component/Plugin/Definition/PluginDefinitionInterface.php
index 1132bb5..04cce59 100644
--- a/core/lib/Drupal/Component/Plugin/Definition/PluginDefinitionInterface.php
+++ b/core/lib/Drupal/Component/Plugin/Definition/PluginDefinitionInterface.php
@@ -10,6 +10,8 @@
 /**
  * Defines a plugin definition.
  *
+ * Object-based plugin definitions SHOULD implement this interface.
+ *
  * @ingroup Plugin
  */
 interface PluginDefinitionInterface {