Issue #3297889: Automated Drupal 10 compatibility fixes

modules/private_message_notify/src/Service/PrivateMessageNotifier.php

@@ -60,6 +60,13 @@ class PrivateMessageNotifier implements PrivateMessageNotifierInterface {
    */
   protected $messageNotifier;
 
+  /**
+   * The module handler.
+   *
+   * @var \Drupal\Core\Extension\ModuleHandlerInterface
+   */
+  protected $moduleHandler;
+
   /**
    * Constructs a new PrivateMessageNotifier object.
    *