Drupal 8.0.0 beta 12. More info: https://www.drupal.org/node/2514176

core/modules/rest/src/ResourceResponse.php

@@ -0,0 +1,57 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\rest\ResourceResponse.
+ */
+
+namespace Drupal\rest;
+
+use Drupal\Core\Cache\CacheableResponseInterface;
+use Drupal\Core\Cache\CacheableResponseTrait;
+use Symfony\Component\HttpFoundation\Response;
+
+/**
+ * Contains data for serialization before sending the response.
+ *
+ * We do not want to abuse the $content property on the Response class to store
+ * our response data. $content implies that the provided data must either be a
+ * string or an object with a __toString() method, which is not a requirement
+ * for data used here.
+ */
+class ResourceResponse extends Response implements CacheableResponseInterface {
+
+  use CacheableResponseTrait;
+
+  /**
+   * Response data that should be serialized.
+   *
+   * @var mixed
+   */
+  protected $responseData;
+
+  /**
+   * Constructor for ResourceResponse objects.
+   *
+   * @param mixed $data
+   *   Response data that should be serialized.
+   * @param int $status
+   *   The response status code.
+   * @param array $headers
+   *   An array of response headers.
+   */
+  public function __construct($data = NULL, $status = 200, $headers = array()) {
+    $this->responseData = $data;
+    parent::__construct('', $status, $headers);
+  }
+
+  /**
+   * Returns response data that should be serialized.
+   *
+   * @return mixed
+   *   Response data that should be serialized.
+   */
+  public function getResponseData() {
+    return $this->responseData;
+  }
+}