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 object of a
+ * different class than the one that originally created the staging area.
+ *
+ * @see \Drupal\package_manager\Stage::destroy()
  */
 class PostDestroyEvent extends StageEvent {
 }