Issue #3257849: Various core quality updates

package_manager/src/Event/PostDestroyEvent.php

@@ -4,6 +4,11 @@ namespace Drupal\package_manager\Event;
 
 /**
  * Event fired after the staging area is destroyed.
+ *
+ * If the stage is being force destroyed ::getStage() may return an instance of
+ * Stage that is different from the instance that created the stage.
+ *
+ * @see \Drupal\package_manager\Stage::destroy()
  */
 class PostDestroyEvent extends StageEvent {
 }