fix `Calling the "Symfony\Component\EventDispatcher\EventDispatcherIn…

…terface::dispatch()" method with the event name as the first argument is deprecated since Symfony 4.3`

app/config/eccube/services.yaml

@@ -29,6 +29,9 @@ services:
           $orderPurchaseFlow: '@eccube.purchase.flow.order'
           $_orderStateMachine: '@state_machine.order'
 
+    event_dispatcher:
+        class: Eccube\Event\EventDispatcherWrapper
+        public: true
 
     # makes classes in src/ available to be used as services
     # this creates a service per class whose id is the fully-qualified class name

src/Eccube/Event/EventDispatcherWrapper.php

@@ -0,0 +1,35 @@
+<?php
+/*
+ * This file is part of EC-CUBE
+ *
+ * Copyright(c) EC-CUBE CO.,LTD. All Rights Reserved.
+ *
+ * http://www.ec-cube.co.jp/
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Eccube\Event;
+
+use Symfony\Component\EventDispatcher\Event;
+use Symfony\Component\EventDispatcher\EventDispatcher;
+
+class EventDispatcherWrapper extends EventDispatcher
+{
+    public function dispatch($event)
+    {
+        $eventName = 1 < \func_num_args() ? func_get_arg(1) : null;
+
+        if (\is_object($event)) {
+            $eventName = $eventName ?? \get_class($event);
+        } elseif (\is_string($event) && (null === $eventName || $eventName instanceof \Symfony\Contracts\EventDispatcher\Event || $eventName instanceof Event)) {
+            $swap = $event;
+            $event = $eventName ?? new Event();
+            $eventName = $swap;
+        }
+
+        return parent::dispatch($event, $eventName);
+    }
+
+}