Avoid serializing "resources" in the normalization context

Author: abluchet

src/EventListener/SerializeListener.php

@@ -16,6 +16,7 @@
 use ApiPlatform\Core\Exception\RuntimeException;
 use ApiPlatform\Core\Serializer\SerializerContextBuilderInterface;
 use ApiPlatform\Core\Util\RequestAttributesExtractor;
+use ApiPlatform\Core\HttpCache\TagsArray;
 use Symfony\Component\HttpFoundation\Request;
 use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\HttpKernel\Event\GetResponseForControllerResultEvent;
@@ -59,13 +60,13 @@ public function onKernelView(GetResponseForControllerResultEvent $event)
         }
 
         $context = $this->serializerContextBuilder->createFromRequest($request, true, $attributes);
-        $resources = [];
+        $resources = new TagsArray();
         $context['resources'] = &$resources;
 
         $event->setControllerResult($this->serializer->serialize($controllerResult, $request->getRequestFormat(), $context));
 
         $request->attributes->set('_api_respond', true);
-        $request->attributes->set('_resources', $request->attributes->get('_resources', []) + $resources);
+        $request->attributes->set('_resources', $request->attributes->get('_resources', []) + (array) $resources);
     }
 
     /**

src/HttpCache/TagsArray.php

@@ -0,0 +1,24 @@
+<?php
+
+/*
+ * This file is part of the API Platform project.
+ *
+ * (c) Kévin Dunglas <[email protected]>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace ApiPlatform\Core\HttpCache;
+
+/**
+ * An ArrayObject that serializes to an empty string to store IRIs
+ *
+ * @author Antoine Bluchet <[email protected]>
+ */
+final class TagsArray extends \ArrayObject
+{
+    public function serialize() {}
+}