diff --git a/core/lib/Drupal/Core/Config/Schema/Sequence.php b/core/lib/Drupal/Core/Config/Schema/Sequence.php
index 4552feb..e66e027 100644
--- a/core/lib/Drupal/Core/Config/Schema/Sequence.php
+++ b/core/lib/Drupal/Core/Config/Schema/Sequence.php
@@ -92,7 +92,7 @@ public function set($index, $value) {
   /**
    * {@inheritdoc}
    */
-  public function drop($index) {
+  public function removeItem($index) {
     $this->offsetUnset($index);
     return $this;
   }
@@ -109,15 +109,6 @@ public function appendItem($value = NULL) {
   /**
    * {@inheritdoc}
    */
-  public function clearItems() {
-    foreach (array_keys($this->getElements()) as $offset) {
-      $this->offsetUnset($offset);
-    }
-  }
-
-  /**
-   * {@inheritdoc}
-   */
   public function filter($callback) {
     $this->value = array_filter($this->value, $callback);
     unset($this->elements);
diff --git a/core/lib/Drupal/Core/TypedData/ListInterface.php b/core/lib/Drupal/Core/TypedData/ListInterface.php
index 33d35ae..5c6cf99 100644
--- a/core/lib/Drupal/Core/TypedData/ListInterface.php
+++ b/core/lib/Drupal/Core/TypedData/ListInterface.php
@@ -69,16 +69,6 @@ public function get($index);
   public function set($index, $value);
 
   /**
-   * Removes the item at the specified position.
-   *
-   * @param int $index
-   *   Index of the item to remove.
-   *
-   * @return $this
-   */
-  public function drop($index);
-
-  /**
    * Returns the first item in this list.
    *
    * @return \Drupal\Core\TypedData\TypedDataInterface
@@ -101,11 +91,14 @@ public function first();
   public function appendItem($value = NULL);
 
   /**
-   * Removes all items from the list.
+   * Removes the item at the specified position.
    *
-   * @return static
+   * @param int $index
+   *   Index of the item to remove.
+   *
+   * @return $this
    */
-  public function clearItems();
+  public function removeItem($index);
 
   /**
    * Filters the items in the list using a custom callback.
diff --git a/core/lib/Drupal/Core/TypedData/Plugin/DataType/ItemList.php b/core/lib/Drupal/Core/TypedData/Plugin/DataType/ItemList.php
index 24a2443..2c7e3ed 100644
--- a/core/lib/Drupal/Core/TypedData/Plugin/DataType/ItemList.php
+++ b/core/lib/Drupal/Core/TypedData/Plugin/DataType/ItemList.php
@@ -141,7 +141,7 @@ public function set($index, $value) {
   /**
    * {@inheritdoc}
    */
-  public function drop($index) {
+  public function removeItem($index) {
     if (!is_numeric($index)) {
       throw new \InvalidArgumentException('Unable to drop a non-numeric delta.');
     }
@@ -180,17 +180,15 @@ public function first() {
    * Implements \ArrayAccess::offsetExists().
    */
   public function offsetExists($offset) {
-    // We do not want to throw exceptions here, so only use get() only when we
-    // are sure it will return.
-// @todo: ask @fago why we need this getValue() !== NULL check to begin with ?
-    return isset($this->list) && array_key_exists($offset, $this->list) && $this->get($offset)->getValue() !== NULL;
+    // We do not want to throw exceptions here, so we do not use get().
+    return isset($this->list[$offset]);
   }
 
   /**
    * Implements \ArrayAccess::offsetUnset().
    */
   public function offsetUnset($offset) {
-    $this->drop($offset);
+    $this->removeItem($offset);
   }
 
   /**
@@ -224,14 +222,6 @@ public function appendItem($value = NULL) {
   }
 
   /**
-   * {@inheritdoc}
-   */
-  public function clearItems() {
-    $this->list = array();
-    return $this;
-  }
-
-  /**
    * Helper for creating a list item object.
    *
    * @return \Drupal\Core\TypedData\TypedDataInterface
diff --git a/core/modules/datetime/src/Tests/DateTimeItemTest.php b/core/modules/datetime/src/Tests/DateTimeItemTest.php
index 2d76079..465326a 100644
--- a/core/modules/datetime/src/Tests/DateTimeItemTest.php
+++ b/core/modules/datetime/src/Tests/DateTimeItemTest.php
@@ -88,7 +88,7 @@ public function testSetValue() {
     // Test DateTimeItem::setValue() using string.
     $entity = entity_create('entity_test');
     $value = '2014-01-01T20:00:00Z';
-    $entity->field_datetime->value = $value;
+    $entity->get('field_datetime')->set(0, $value);
     $entity->save();
     // Load the entity and ensure the field was saved correctly.
     $id = $entity->id();
@@ -98,7 +98,7 @@ public function testSetValue() {
     // Test DateTimeItem::setValue() using property array.
     $entity = entity_create('entity_test');
     $value = '2014-01-01T20:00:00Z';
-    $entity->field_datetime->value = $value;
+    $entity->set('field_datetime', $value);
     $entity->save();
     // Load the entity and ensure the field was saved correctly.
     $id = $entity->id();
diff --git a/core/modules/hal/src/Normalizer/ContentEntityNormalizer.php b/core/modules/hal/src/Normalizer/ContentEntityNormalizer.php
index 3a4432a..e7919f7 100644
--- a/core/modules/hal/src/Normalizer/ContentEntityNormalizer.php
+++ b/core/modules/hal/src/Normalizer/ContentEntityNormalizer.php
@@ -186,7 +186,7 @@ public function denormalize($data, $class, $format = NULL, array $context = arra
       // Remove any values that were set as a part of entity creation (e.g
       // uuid). If the incoming field data is set to an empty array, this will
       // also have the effect of emptying the field in REST module.
-      $items->clearItems();
+      $items->setValue(array());
       if ($field_data) {
         // Denormalize the field data into the FieldItemList object.
         $context['target_instance'] = $items;