Update to drupal 8.0.0-rc1. For more information, see https://www.drupal.org/node/2582663

vendor/symfony/serializer/Mapping/AttributeMetadata.php

@@ -0,0 +1,94 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Serializer\Mapping;
+
+/**
+ * {@inheritdoc}
+ *
+ * @author Kévin Dunglas <dunglas@gmail.com>
+ */
+class AttributeMetadata implements AttributeMetadataInterface
+{
+    /**
+     * @var string
+     *
+     * @internal This property is public in order to reduce the size of the
+     *           class' serialized representation. Do not access it. Use
+     *           {@link getName()} instead.
+     */
+    public $name;
+
+    /**
+     * @var array
+     *
+     * @internal This property is public in order to reduce the size of the
+     *           class' serialized representation. Do not access it. Use
+     *           {@link getGroups()} instead.
+     */
+    public $groups = array();
+
+    /**
+     * Constructs a metadata for the given attribute.
+     *
+     * @param string $name
+     */
+    public function __construct($name)
+    {
+        $this->name = $name;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getName()
+    {
+        return $this->name;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function addGroup($group)
+    {
+        if (!in_array($group, $this->groups)) {
+            $this->groups[] = $group;
+        }
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getGroups()
+    {
+        return $this->groups;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function merge(AttributeMetadataInterface $attributeMetadata)
+    {
+        foreach ($attributeMetadata->getGroups() as $group) {
+            $this->addGroup($group);
+        }
+    }
+
+    /**
+     * Returns the names of the properties that should be serialized.
+     *
+     * @return string[]
+     */
+    public function __sleep()
+    {
+        return array('name', 'groups');
+    }
+}