добавил еще дто в ответ

Author: Denis Korolev

src/Entities/Document/Common/ChangesAction.php

@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace MagDv\Sbis\Entities\Document\Common;
+
+use JMS\Serializer\Annotation as Serializer;
+
+class ChangesAction
+{
+    /**
+     * @Serializer\SerializedName("Идентификатор")
+     * @Serializer\Type("string")
+     */
+    public ?string $id = null;
+
+    /**
+     * @Serializer\SerializedName("Название")
+     * @Serializer\Type("string")
+     */
+    public ?string $name = null;
+}

src/Entities/Document/Common/Event.php

@@ -45,4 +45,11 @@ class Event
      * @Serializer\Type("string")
      */
     public ?string $name = null;
+
+    /**
+     * @var ChangesAction|null
+     * @Serializer\SerializedName("Действие")
+     * @Serializer\Type("MagDv\Sbis\Entities\Document\Common\ChangesAction")
+     */
+    public ?ChangesAction $action = null;
 }