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

vendor/zendframework/zend-diactoros/src/Response/EmitterInterface.php

@@ -0,0 +1,32 @@
+<?php
+/**
+ * Zend Framework (http://framework.zend.com/)
+ *
+ * @see       http://github.com/zendframework/zend-diactoros for the canonical source repository
+ * @copyright Copyright (c) 2015 Zend Technologies USA Inc. (http://www.zend.com)
+ * @license   https://github.com/zendframework/zend-diactoros/blob/master/LICENSE.md New BSD License
+ */
+
+namespace Zend\Diactoros\Response;
+
+use Psr\Http\Message\ResponseInterface;
+
+interface EmitterInterface
+{
+    /**
+     * Emit a response.
+     *
+     * Emits a response, including status line, headers, and the message body,
+     * according to the environment.
+     *
+     * Implementations of this method may be written in such a way as to have
+     * side effects, such as usage of header() or pushing output to the
+     * output buffer.
+     *
+     * Implementations MAY raise exceptions if they are unable to emit the
+     * response; e.g., if headers have already been sent.
+     *
+     * @param ResponseInterface $response
+     */
+    public function emit(ResponseInterface $response);
+}