Issue #2660026 by theMusician: Remove obsolete...

Issue #2660026 by theMusician: Remove obsolete \Drupal\Core\Config\Entity\ConfigEntityBase::$pluginConfigKey

core/lib/Drupal/Core/Config/Entity/ConfigEntityBase.php

@@ -39,16 +39,6 @@ abstract class ConfigEntityBase extends Entity implements ConfigEntityInterface
    */
   protected $originalId;
 
-  /**
-   * The name of the property that is used to store plugin configuration.
-   *
-   * This is needed when the entity uses a LazyPluginCollection, to dictate
-   * where the plugin configuration should be stored.
-   *
-   * @var string
-   */
-  protected $pluginConfigKey;
-
   /**
    * The enabled/disabled status of the configuration entity.
    *