diff --git a/core/lib/Drupal/Core/Template/Attribute.php b/core/lib/Drupal/Core/Template/Attribute.php
index 9798b52..8859a3b 100644
--- a/core/lib/Drupal/Core/Template/Attribute.php
+++ b/core/lib/Drupal/Core/Template/Attribute.php
@@ -263,6 +263,9 @@ public function __toString() {
 
   /**
    * Returns all storage elements as an array.
+   *
+   * @return array
+   *   An associative array of attributes.
    */
   public function toArray() {
     $return = [];