diff --git a/core/lib/Drupal/Core/TypedData/ComplexDataInterface.php b/core/lib/Drupal/Core/TypedData/ComplexDataInterface.php
index 0a5b38a..e7b91fc 100644
--- a/core/lib/Drupal/Core/TypedData/ComplexDataInterface.php
+++ b/core/lib/Drupal/Core/TypedData/ComplexDataInterface.php
@@ -100,13 +100,4 @@ public function toArray();
    */
   public function isEmpty();
 
-  /**
-   * React to changes to a child property.
-   *
-   * Note that this is invoked after any changes have been applied.
-   *
-   * @param $property_name
-   *   The name of the property which is changed.
-   */
-  public function onChange($property_name);
 }
diff --git a/core/lib/Drupal/Core/TypedData/ListInterface.php b/core/lib/Drupal/Core/TypedData/ListInterface.php
index 2c5dbc7..4e78b48 100644
--- a/core/lib/Drupal/Core/TypedData/ListInterface.php
+++ b/core/lib/Drupal/Core/TypedData/ListInterface.php
@@ -39,16 +39,6 @@ public function isEmpty();
   public function getItemDefinition();
 
   /**
-   * React to changes to a child item.
-   *
-   * Note that this is invoked after any changes have been applied.
-   *
-   * @param $delta
-   *   The delta of the item which is changed.
-   */
-  public function onChange($delta);
-
-  /**
    * Returns the item at the specified position in this list.
    *
    * @param int $index
diff --git a/core/lib/Drupal/Core/TypedData/TraversableTypedDataInterface.php b/core/lib/Drupal/Core/TypedData/TraversableTypedDataInterface.php
index d42557e..34b1df5 100644
--- a/core/lib/Drupal/Core/TypedData/TraversableTypedDataInterface.php
+++ b/core/lib/Drupal/Core/TypedData/TraversableTypedDataInterface.php
@@ -10,4 +10,16 @@
 /**
  * An interface for typed data objects that can be traversed.
  */
-interface TraversableTypedDataInterface extends TypedDataInterface, \Traversable {}
+interface TraversableTypedDataInterface extends TypedDataInterface, \Traversable {
+
+  /**
+   * React to changes to a child property or item.
+   *
+   * Note that this is invoked after any changes have been applied.
+   *
+   * @param $name
+   *   The name of the property or the delta of the list item which is changed.
+   */
+  public function onChange($name);
+
+}