diff --git a/core/lib/Drupal/Core/Entity/ContentEntityBase.php b/core/lib/Drupal/Core/Entity/ContentEntityBase.php
index 826193b..b776608 100644
--- a/core/lib/Drupal/Core/Entity/ContentEntityBase.php
+++ b/core/lib/Drupal/Core/Entity/ContentEntityBase.php
@@ -375,9 +375,9 @@ protected function getTranslatedField($name, $langcode) {
    * {@inheritdoc}
    */
   public function set($name, $value, $notify = TRUE) {
-    // If default language or an entity key changes we need to react to that.
-    $notify = $name == 'langcode' || in_array($name, $this->getEntityType()->getKeys());
-    $this->get($name)->setValue($value, $notify);
+    $this->get($name)->setValue($value, FALSE);
+    // Directly notify ourselves, so we can take changes into account.
+    $this->onChange($name);
   }
 
   /**
diff --git a/core/lib/Drupal/Core/Field/FieldItemBase.php b/core/lib/Drupal/Core/Field/FieldItemBase.php
index b9c90d9..62d1a3d 100644
--- a/core/lib/Drupal/Core/Field/FieldItemBase.php
+++ b/core/lib/Drupal/Core/Field/FieldItemBase.php
@@ -191,26 +191,26 @@ public function __isset($name) {
    * {@inheritdoc}
    */
   public function __unset($name) {
-    // Explicitly unset the property in $this->values if a non-defined
-    // property is unset, such that its key is removed from $this->values.
-    if (!$this->definition->getPropertyDefinition($name)) {
-      unset($this->values[$name]);
+    if ($this->definition->getPropertyDefinition($name)) {
+      $this->set($name, NULL);
     }
     else {
-      $this->set($name, NULL);
+      // Explicitly unset the property in $this->values if a non-defined
+      // property is unset, such that its key is removed from $this->values.
+      unset($this->values[$name]);
     }
   }
 
   /**
    * {@inheritdoc}
    */
-  public function onChange($property_name) {
+  public function onChange($property_name, $notify = TRUE) {
     // Remove the plain value, such that any further __get() calls go via the
     // updated property object.
     if (isset($this->properties[$property_name])) {
       unset($this->values[$property_name]);
     }
-    parent::onChange($property_name);
+    parent::onChange($property_name, $notify);
   }
 
   /**
diff --git a/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
index a6c6bed..317befd 100644
--- a/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
+++ b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
@@ -175,7 +175,11 @@ public function getValue($include_computed = FALSE) {
   /**
    * {@inheritdoc}
    */
-  public function onChange($property_name) {
+  public function onChange($property_name, $notify = TRUE) {
+    // Let the parent class do its work first, such that $this->values and
+    // $this->properties are in sync.
+    parent::onChange($property_name, FALSE);
+
     // Make sure that the target ID and the target property stay in sync.
     if ($property_name == 'target_id') {
       $this->properties['entity']->setValue($this->target_id, FALSE);
@@ -183,7 +187,11 @@ public function onChange($property_name) {
     elseif ($property_name == 'entity') {
       $this->set('target_id', $this->properties['entity']->getTargetIdentifier(), FALSE);
     }
-    parent::onChange($property_name);
+
+    // Notify the parent of changes.
+    if (isset($this->parent) && $notify) {
+      $this->parent->onChange($this->name);
+    }
   }
 
   /**
diff --git a/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/LanguageItem.php b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/LanguageItem.php
index 961eb67..7d0329b 100644
--- a/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/LanguageItem.php
+++ b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/LanguageItem.php
@@ -100,7 +100,11 @@ public function applyDefaultValue($notify = TRUE) {
   /**
    * {@inheritdoc}
    */
-  public function onChange($property_name) {
+  public function onChange($property_name, $notify = TRUE) {
+    // Let the parent class do its work first, such that $this->values and
+    // $this->properties are in sync.
+    parent::onChange($property_name, FALSE);
+
     // Make sure that the value and the language property stay in sync.
     if ($property_name == 'value') {
       $this->properties['language']->setValue($this->value, FALSE);
@@ -108,6 +112,11 @@ public function onChange($property_name) {
     elseif ($property_name == 'language') {
       $this->set('value', $this->properties['language']->getTargetIdentifier(), FALSE);
     }
-    parent::onChange($property_name);
+
+    // Notify the parent of changes.
+    if (isset($this->parent) && $notify) {
+      $this->parent->onChange($this->name);
+    }
   }
+
 }
diff --git a/core/lib/Drupal/Core/TypedData/Plugin/DataType/Map.php b/core/lib/Drupal/Core/TypedData/Plugin/DataType/Map.php
index e17e072..408c0cc 100644
--- a/core/lib/Drupal/Core/TypedData/Plugin/DataType/Map.php
+++ b/core/lib/Drupal/Core/TypedData/Plugin/DataType/Map.php
@@ -213,11 +213,16 @@ public function __clone() {
   }
 
   /**
-   * Implements \Drupal\Core\TypedData\ComplexDataInterface::onChange().
+   * {@inheritdoc}
+   *
+   * @param bool $notify
+   *   (optional) Whether to forward the notification to the parent. Defaults to
+   *   TRUE. By passing FALSE overriding implementations can re-use the logic
+   *   of parent classes without triggering the parent notification.
    */
-  public function onChange($property_name) {
+  public function onChange($property_name, $notify = TRUE) {
     // Notify the parent of changes.
-    if (isset($this->parent)) {
+    if (isset($this->parent) && $notify) {
       $this->parent->onChange($this->name);
     }
   }
diff --git a/core/modules/datetime/src/Plugin/Field/FieldType/DateTimeItem.php b/core/modules/datetime/src/Plugin/Field/FieldType/DateTimeItem.php
index d24f1c2..6ecf319 100644
--- a/core/modules/datetime/src/Plugin/Field/FieldType/DateTimeItem.php
+++ b/core/modules/datetime/src/Plugin/Field/FieldType/DateTimeItem.php
@@ -131,12 +131,12 @@ public function isEmpty() {
   /**
    * {@inheritdoc}
    */
-  public function onChange($property_name) {
+  public function onChange($property_name, $notify = TRUE) {
     // Enforce that the computed date is recalculated.
     if ($property_name == 'value') {
       $this->date = NULL;
     }
-    parent::onChange($property_name);
+    parent::onChange($property_name, $notify);
   }
 
 }
diff --git a/core/modules/system/src/Tests/Entity/EntityFieldTest.php b/core/modules/system/src/Tests/Entity/EntityFieldTest.php
index e975e9f..45709b9 100644
--- a/core/modules/system/src/Tests/Entity/EntityFieldTest.php
+++ b/core/modules/system/src/Tests/Entity/EntityFieldTest.php
@@ -169,12 +169,12 @@ protected function doTestReadWrite($entity_type) {
     // Create a fresh entity so target_id does not get its property object
     // instantiated, then verify setting a new value via typed data API works.
     $entity2 = entity_create($entity_type, array(
-      'user_id' => array('target_id' => $new_user2->id()),
+      'user_id' => array('target_id' => $new_user1->id()),
     ));
     // Access the property object, and set a value.
     $entity2->user_id->first()->get('target_id')->setValue($new_user2->id());
     $this->assertEqual($new_user2->id(), $entity2->user_id->target_id, format_string('%entity_type: Updated user id can be read.', array('%entity_type' => $entity_type)));
-    $this->assertEqual($new_user2->getUsername(), $entity2->user_id->entity->name->value, format_string('%entity_type: Updated user name value can be read.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($new_user2->name->value, $entity2->user_id->entity->name->value, format_string('%entity_type: Updated user name value can be read.', array('%entity_type' => $entity_type)));
 
     // Test using isset(), empty() and unset().
     $entity->name->value = 'test unset';
diff --git a/core/modules/text/src/Plugin/Field/FieldType/TextItemBase.php b/core/modules/text/src/Plugin/Field/FieldType/TextItemBase.php
index 3d81f31..17b7ef0 100644
--- a/core/modules/text/src/Plugin/Field/FieldType/TextItemBase.php
+++ b/core/modules/text/src/Plugin/Field/FieldType/TextItemBase.php
@@ -59,7 +59,7 @@ public function isEmpty() {
   /**
    * {@inheritdoc}
    */
-  public function onChange($property_name) {
+  public function onChange($property_name, $notify = TRUE) {
     // Unset processed properties that are affected by the change.
     foreach ($this->definition->getPropertyDefinitions() as $property => $definition) {
       if ($definition->getClass() == '\Drupal\text\TextProcessed') {
@@ -68,7 +68,7 @@ public function onChange($property_name) {
         }
       }
     }
-    parent::onChange($property_name);
+    parent::onChange($property_name, $notify);
   }
 
   /**