diff -u b/core/lib/Drupal/Core/Render/CacheableStreamedResponseInterface.php b/core/lib/Drupal/Core/Render/CacheableStreamedResponseInterface.php
--- b/core/lib/Drupal/Core/Render/CacheableStreamedResponseInterface.php
+++ b/core/lib/Drupal/Core/Render/CacheableStreamedResponseInterface.php
@@ -21,7 +21,7 @@
    *
    * @see \Symfony\Component\HttpKernel\KernelEvents::RESPONSE
    *
-   * @return FALSE|\Drupal\Core\Cache\CacheableResponseInterface
+   * @return false|\Drupal\Core\Cache\CacheableResponseInterface
    */
   public function getCacheableStreamedResponse();