diff --git a/core/lib/Drupal/Core/Render/RendererInterface.php b/core/lib/Drupal/Core/Render/RendererInterface.php
index 1344c5631b..f3693ab583 100644
--- a/core/lib/Drupal/Core/Render/RendererInterface.php
+++ b/core/lib/Drupal/Core/Render/RendererInterface.php
@@ -233,24 +233,24 @@ public function renderPlaceholder($placeholder, array $elements);
    *   of overrides as the value in #theme_wrappers array.
    *   For example, if we have a render element as follows:
    *   @code
-   *   array(
+   *   [
    *     '#theme' => 'image',
-   *     '#attributes' => array('class' => array('foo')),
-   *     '#theme_wrappers' => array('container'),
-   *   );
+   *     '#attributes' => ['class' => ['foo']],
+   *     '#theme_wrappers' => ['container'],
+   *   ];
    *   @endcode
    *   and we need to pass the class 'bar' as an attribute for 'container', we
    *   can rewrite our element thus:
    *   @code
-   *   array(
+   *   [
    *     '#theme' => 'image',
-   *     '#attributes' => array('class' => array('foo')),
-   *     '#theme_wrappers' => array(
-   *       'container' => array(
-   *         '#attributes' => array('class' => array('bar')),
-   *       ),
-   *     ),
-   *   );
+   *     '#attributes' => ['class' => ['foo']],
+   *     '#theme_wrappers' => [
+   *       'container' => [
+   *         '#attributes' => ['class' => ['bar']],
+   *       ],
+   *     ],
+   *   ];
    *    @endcode
    * - If this element has an array of #post_render functions defined, they
    *   are called sequentially to modify the rendered #children. Unlike