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

vendor/symfony/serializer/Normalizer/NormalizableInterface.php

@@ -0,0 +1,39 @@
+<?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\Normalizer;
+
+/**
+ * Defines the most basic interface a class must implement to be normalizable.
+ *
+ * If a normalizer is registered for the class and it doesn't implement
+ * the Normalizable interfaces, the normalizer will be used instead.
+ *
+ * @author Jordi Boggiano <j.boggiano@seld.be>
+ */
+interface NormalizableInterface
+{
+    /**
+     * Normalizes the object into an array of scalars|arrays.
+     *
+     * It is important to understand that the normalize() call should normalize
+     * recursively all child objects of the implementor.
+     *
+     * @param NormalizerInterface $normalizer The normalizer is given so that you
+     *                                        can use it to normalize objects contained within this object.
+     * @param string|null         $format     The format is optionally given to be able to normalize differently
+     *                                        based on different output formats.
+     * @param array               $context    Options for normalizing this object
+     *
+     * @return array|string|bool|int|float|null
+     */
+    public function normalize(NormalizerInterface $normalizer, $format = null, array $context = array());
+}