+ /**
+ * Fires when a custom plugin or theme update request is received.
+ *
+ * The dynamic portion of the hook name, $action, refers to the action
+ * provided in the request for wp-admin/update.php. Can be used to
+ * provide custom update functionality for themes and plugins.
+ *
+ * @since 2.8.0
+ */
+ do_action( "update-custom_{$action}" );