diff --git a/core/lib/Drupal/Core/TypedData/ComputedItemListTrait.php b/core/lib/Drupal/Core/TypedData/ComputedItemListTrait.php
index 182a946..7a823a4 100644
--- a/core/lib/Drupal/Core/TypedData/ComputedItemListTrait.php
+++ b/core/lib/Drupal/Core/TypedData/ComputedItemListTrait.php
@@ -13,6 +13,8 @@
  * @ingroup typed_data
  *
  * @internal
+ *   This trait has been added in Drupal 8.4.3 as an internal helper and should
+ *   not be used outside of core.
  */
 trait ComputedItemListTrait {