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

vendor/symfony/validator/ClassBasedInterface.php

@@ -0,0 +1,30 @@
+<?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\Validator;
+
+/**
+ * An object backed by a PHP class.
+ *
+ * @author Bernhard Schussek <bschussek@gmail.com>
+ *
+ * @deprecated since version 2.5, to be removed in 3.0.
+ *             Use {@link Mapping\ClassMetadataInterface} instead.
+ */
+interface ClassBasedInterface
+{
+    /**
+     * Returns the name of the backing PHP class.
+     *
+     * @return string The name of the backing class.
+     */
+    public function getClassName();
+}