diff --git a/core/lib/Drupal/Core/Field/Plugin/Field/FieldWidget/TimestampWidget.php b/core/lib/Drupal/Core/Field/Plugin/Field/FieldWidget/TimestampWidget.php
index a309a9b..fc487de 100644
--- a/core/lib/Drupal/Core/Field/Plugin/Field/FieldWidget/TimestampWidget.php
+++ b/core/lib/Drupal/Core/Field/Plugin/Field/FieldWidget/TimestampWidget.php
@@ -48,10 +48,15 @@ public function formElement(FieldItemListInterface $items, $delta, array $elemen
       ),
     );
 
-    $timestamp = (int) $items[$delta]->value;
-    $created_timestamp = (int) $items->getEntity()->getCreatedTime();
-    $element['value']['#description'] = $this->t('Format: %time. The date format is YYYY-MM-DD and %timezone is the time zone offset from UTC. Leave blank to use the time of form submission.', array('%time' => !empty($default_value) ?
-        date_format(date_create($default_value), 'Y-m-d H:i:s O') : format_date($created_timestamp, 'custom', 'Y-m-d H:i:s O'), '%timezone' => !empty($default_value) ? date_format(date_create($default_value), 'O') : format_date($created_timestamp, 'custom', 'O')));
+    if (!empty($default_value)) {
+      $example_time = date_format(date_create($default_value), 'Y-m-d H:i:s O');
+      $timezone = date_format(date_create($default_value), 'O');
+    }
+    else {
+      $example_time = format_date(REQUEST_TIME, 'custom', 'Y-m-d H:i:s O');
+      $timezone = format_date(REQUEST_TIME, 'custom', 'O');
+    }
+    $element['value']['#description'] = $this->t('Format: %time. The date format is YYYY-MM-DD and %timezone is the time zone offset from UTC. Leave blank to use the time of form submission.', array('%time' => $example_time, '%timezone' => $timezone));
 
     return $element;
   }
diff --git a/core/modules/node/src/Tests/PageEditTest.php b/core/modules/node/src/Tests/PageEditTest.php
index ff97e9a..4fc20db 100644
--- a/core/modules/node/src/Tests/PageEditTest.php
+++ b/core/modules/node/src/Tests/PageEditTest.php
@@ -7,6 +7,8 @@
 
 namespace Drupal\node\Tests;
 
+use Drupal\Component\Utility\String;
+
 /**
  * Tests the node edit functionality.
  */
@@ -117,7 +119,7 @@ function testPageAuthoredBy() {
       'uid[0][target_id]' => 'invalid-name',
     );
     $this->drupalPostForm('node/' . $node->id() . '/edit', $edit, t('Save and keep published'));
-    $this->assertRaw(format_string('The username %name does not exist.', array('%name' => 'invalid-name')));
+    $this->assertRaw(String::format('The username %name does not exist.', array('%name' => 'invalid-name')));
 
     // Change the authored by field to an empty string, which should assign
     // authorship to the anonymous user (uid 0).
diff --git a/core/modules/rdf/rdf.module b/core/modules/rdf/rdf.module
index 279cde2..e56ab9a 100644
--- a/core/modules/rdf/rdf.module
+++ b/core/modules/rdf/rdf.module
@@ -216,7 +216,7 @@ function rdf_entity_prepare_view($entity_type, array $entities, array $displays)
       $field_mapping = $mapping->getPreparedFieldMapping($name);
       if ($field_mapping) {
         foreach ($entity->get($name) as $item) {
-          $item->_attributes += rdf_rdfa_attributes($field_mapping, $item->getValue());
+          $item->_attributes += rdf_rdfa_attributes($field_mapping, $item->toArray());
         }
       }
     }
@@ -233,7 +233,7 @@ function rdf_comment_load($comments) {
     // to optimize performance for websites that implement an entity cache.
     $created_mapping = rdf_get_mapping('comment', $comment->bundle())
       ->getPreparedFieldMapping('created');
-    $comment->rdf_data['date'] = rdf_rdfa_attributes($created_mapping, $comment->get('created')[0]->getValue());
+    $comment->rdf_data['date'] = rdf_rdfa_attributes($created_mapping, $comment->get('created')->first()->toArray());
     $entity = $comment->getCommentedEntity();
     $comment->rdf_data['entity_uri'] = $entity->url();
     if ($comment->hasParentComment()) {
diff --git a/core/lib/Drupal/Core/Field/Plugin/Field/FieldFormatter/AuthorFormatter.php b/core/modules/user/src/Plugin/Field/FieldFormatter/AuthorFormatter.php
similarity index 88%
rename from core/lib/Drupal/Core/Field/Plugin/Field/FieldFormatter/AuthorFormatter.php
rename to core/modules/user/src/Plugin/Field/FieldFormatter/AuthorFormatter.php
index 2410202..38c7f55 100644
--- a/core/lib/Drupal/Core/Field/Plugin/Field/FieldFormatter/AuthorFormatter.php
+++ b/core/modules/user/src/Plugin/Field/FieldFormatter/AuthorFormatter.php
@@ -2,10 +2,10 @@
 
 /**
  * @file
- * Contains \Drupal\Core\Field\Plugin\Field\FieldFormatter\AuthorFormatter.
+ * Contains \Drupal\user\Plugin\Field\FieldFormatter\AuthorFormatter.
  */
 
-namespace Drupal\Core\Field\Plugin\Field\FieldFormatter;
+namespace Drupal\user\Plugin\Field\FieldFormatter;
 
 use Drupal\Core\Field\FieldItemListInterface;
 use Drupal\Core\Field\FormatterBase;
diff --git a/core/lib/Drupal/Core/Field/Plugin/Field/FieldWidget/AuthorAutocompleteWidget.php b/core/modules/user/src/Plugin/Field/FieldWidget/AuthorAutocompleteWidget.php
similarity index 89%
rename from core/lib/Drupal/Core/Field/Plugin/Field/FieldWidget/AuthorAutocompleteWidget.php
rename to core/modules/user/src/Plugin/Field/FieldWidget/AuthorAutocompleteWidget.php
index 09e74f8..107f0e6 100644
--- a/core/lib/Drupal/Core/Field/Plugin/Field/FieldWidget/AuthorAutocompleteWidget.php
+++ b/core/modules/user/src/Plugin/Field/FieldWidget/AuthorAutocompleteWidget.php
@@ -5,9 +5,10 @@
  * Contains \Drupal\Core\Field\Plugin\Field\FieldWidget\RouteBasedAutocompleteWidget.
  */
 
-namespace Drupal\Core\Field\Plugin\Field\FieldWidget;
+namespace Drupal\user\Plugin\Field\FieldWidget;
 
 use Drupal\Core\Field\FieldItemListInterface;
+use Drupal\Core\Field\Plugin\Field\FieldWidget\RouteBasedAutocompleteWidget;
 use Drupal\Core\Field\WidgetBase;
 
 /**
@@ -29,8 +30,7 @@ class AuthorAutocompleteWidget extends RouteBasedAutocompleteWidget {
   public function formElement(FieldItemListInterface $items, $delta, array $element, array &$form, array &$form_state) {
     $element = parent::formElement($items, $delta, $element, $form, $form_state);
 
-    $entity = $items->getEntity();
-    $element['target_id']['#default_value'] = $entity->getOwner()->isAuthenticated() ? $entity->getOwner()->getUsername() : '';
+    $element['target_id']['#default_value'] = $items[$delta]->entity->isAuthenticated() ? $items[$delta]->entity->getUsername() : '';
 
     $user_config = \Drupal::config('user.settings');
     $element['target_id']['#description'] = $this->t('Leave blank for %anonymous.', array('%anonymous' => $user_config->get('anonymous')));