diff --git a/core/lib/Drupal/Core/Entity/Field/Type/EntityReferenceItem.php b/core/lib/Drupal/Core/Entity/Field/Type/EntityReferenceItem.php
index bdb592c..a55bc75 100644
--- a/core/lib/Drupal/Core/Entity/Field/Type/EntityReferenceItem.php
+++ b/core/lib/Drupal/Core/Entity/Field/Type/EntityReferenceItem.php
@@ -11,7 +11,7 @@
 use Drupal\Core\TypedData\ContextAwareInterface;
 
 /**
- * Defines the 'entityre_reference_field' entity field item.
+ * Defines the 'entityre_reference' entity field item.
  *
  * Required settings (below the definition's 'settings' key) are:
  *  - target_type: The entity type to reference.
@@ -31,6 +31,7 @@ class EntityReferenceItem extends FieldItemBase {
    * Implements Drupal\Core\TypedData\ComplexDataInterface::getPropertyDefinitions().
    */
   public function getPropertyDefinitions() {
+    // Definitions vary by entity type, so key them by entity type.
     $target_type = $this->definition['settings']['target_type'];
 
     if (!isset(self::$propertyDefinitions[$target_type])) {
diff --git a/core/modules/entity_reference/entity_reference.module b/core/modules/entity_reference/entity_reference.module
index e9248b0..fcf3ef5 100644
--- a/core/modules/entity_reference/entity_reference.module
+++ b/core/modules/entity_reference/entity_reference.module
@@ -36,6 +36,10 @@ function entity_reference_field_info() {
 
 /**
  * Implements hook_entity_field_info().
+ *
+ * Set the "target_type" property definition for entity reference fields.
+ *
+ * @see Drupal\Core\Entity\Field\Type\EntityReferenceItem::getPropertyDefinitions()
  */
 function entity_reference_entity_field_info($entity_type) {
   $property_info = array();
diff --git a/core/modules/system/lib/Drupal/system/Tests/Entity/EntityUUIDTest.php b/core/modules/system/lib/Drupal/system/Tests/Entity/EntityUUIDTest.php
index 8995301..88a2509 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Entity/EntityUUIDTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Entity/EntityUUIDTest.php
@@ -81,9 +81,7 @@ function testCRUD() {
           $this->assertNotEqual($entity_duplicate->id(), $entity->id());
           break;
         default:
-          // @todo: Use the property data to extract the key.
-          $key = $property == 'user_id' ? 'target_id' : 'value';
-          $this->assertEqual($entity_duplicate->{$property}->{$key}, $entity->{$property}->{$key});
+          $this->assertEqual($entity_duplicate->{$property}->getValue(), $entity->{$property}->getValue());
       }
     }
     $entity_duplicate->save();
diff --git a/core/modules/translation_entity/translation_entity.pages.inc b/core/modules/translation_entity/translation_entity.pages.inc
index 385480b..13afc7d 100644
--- a/core/modules/translation_entity/translation_entity.pages.inc
+++ b/core/modules/translation_entity/translation_entity.pages.inc
@@ -209,10 +209,7 @@ function translation_entity_prepare_translation(EntityInterface $entity, Languag
     $source_translation = $entity->getTranslation($source->langcode);
     $target_translation = $entity->getTranslation($target->langcode);
     foreach ($target_translation->getPropertyDefinitions() as $property_name => $definition) {
-      // @todo The "key" part should not be needed. Remove it as soon as things
-      // do not break.
-      $key = key($entity->{$property_name}[0]->getProperties());
-      $target_translation->$property_name->{$key} = $source_translation->$property_name->{$key};
+      $target_translation->$property_name = $source_translation->$property_name;
     }
   }
   else {