reverted:
--- b/core/lib/Drupal/Core/DrupalKernel.php
+++ a/core/lib/Drupal/Core/DrupalKernel.php
@@ -15,7 +15,7 @@
 use Drupal\Core\DependencyInjection\ServiceProviderInterface;
 use Drupal\Core\DependencyInjection\YamlFileLoader;
 use Drupal\Core\Extension\ExtensionDiscovery;
+use Drupal\Core\Language\Language;
-use Drupal\Core\Language\LanguageInterface;
 use Symfony\Component\Config\Loader\LoaderInterface;
 use Symfony\Component\DependencyInjection\ParameterBag\ParameterBag;
 use Symfony\Component\DependencyInjection\Dumper\PhpDumper;
@@ -519,7 +519,7 @@
     // avoids the circular dependencies that would created by
     // \Drupal\language\LanguageServiceProvider::alter() and allows the default
     // language to not be English in the installer.
+    $default_language_values = Language::$defaultValues;
-    $default_language_values = LanguageInterface::$defaultValues;
     if ($system = $this->getConfigStorage()->read('system.site')) {
       if ($default_language_values['id'] != $system['langcode']) {
         $default_language_values = array('id' => $system['langcode'], 'default' => TRUE);
diff -u b/core/modules/block/custom_block/lib/Drupal/custom_block/CustomBlockForm.php b/core/modules/block/custom_block/lib/Drupal/custom_block/CustomBlockForm.php
--- b/core/modules/block/custom_block/lib/Drupal/custom_block/CustomBlockForm.php
+++ b/core/modules/block/custom_block/lib/Drupal/custom_block/CustomBlockForm.php
@@ -109,7 +109,7 @@
     $form['langcode'] = array(
       '#title' => $this->t('Language'),
       '#type' => 'language_select',
-      '#default_value' => $block->getUntranslated()->language()->id,
+      '#default_value' => $block->getUntranslated()->language()->getId(),
       '#languages' => LanguageInterface::STATE_ALL,
       '#access' => isset($language_configuration['language_show']) && $language_configuration['language_show'],
     );
diff -u b/core/modules/content_translation/content_translation.module b/core/modules/content_translation/content_translation.module
--- b/core/modules/content_translation/content_translation.module
+++ b/core/modules/content_translation/content_translation.module
@@ -709,7 +709,7 @@
     // @todo Avoid using request attributes once translation metadata become
     //   regular fields.
     $attributes = \Drupal::request()->attributes;
-    \Drupal::service('content_translation.synchronizer')->synchronizeFields($entity, $entity->language()->id, $attributes->get('source_langcode'));
+    \Drupal::service('content_translation.synchronizer')->synchronizeFields($entity, $entity->language()->getId(), $attributes->get('source_langcode'));
   }
 }
 
diff -u b/core/modules/content_translation/content_translation.pages.inc b/core/modules/content_translation/content_translation.pages.inc
--- b/core/modules/content_translation/content_translation.pages.inc
+++ b/core/modules/content_translation/content_translation.pages.inc
@@ -21,7 +21,7 @@
 function content_translation_overview(EntityInterface $entity) {
   $controller = content_translation_controller($entity->getEntityTypeId());
   $languages = \Drupal::languageManager()->getLanguages();
-  $original = $entity->getUntranslated()->language()->id;
+  $original = $entity->getUntranslated()->language()->getId();
   $translations = $entity->getTranslationLanguages();
   $administrator = \Drupal::currentUser()->hasPermission('administer languages');
 
diff -u b/core/modules/content_translation/lib/Drupal/content_translation/Access/ContentTranslationManageAccessCheck.php b/core/modules/content_translation/lib/Drupal/content_translation/Access/ContentTranslationManageAccessCheck.php
--- b/core/modules/content_translation/lib/Drupal/content_translation/Access/ContentTranslationManageAccessCheck.php
+++ b/core/modules/content_translation/lib/Drupal/content_translation/Access/ContentTranslationManageAccessCheck.php
@@ -69,7 +69,7 @@
           $language = language_load($request->attributes->get('language'));
           $language = !empty($language) ? $language : \Drupal::languageManager()->getCurrentLanguage(LanguageInterface::TYPE_CONTENT);
           return isset($languages[$language->getId()])
-            && $language->getId() != $entity->getUntranslated()->language()->id
+            && $language->getId() != $entity->getUntranslated()->language()->getId()
             && isset($translations[$language->getId()])
             && $controller->getTranslationAccess($entity, $operation)
             ? static::ALLOW : static::DENY;
diff -u b/core/modules/content_translation/lib/Drupal/content_translation/ContentTranslationHandler.php b/core/modules/content_translation/lib/Drupal/content_translation/ContentTranslationHandler.php
--- b/core/modules/content_translation/lib/Drupal/content_translation/ContentTranslationHandler.php
+++ b/core/modules/content_translation/lib/Drupal/content_translation/ContentTranslationHandler.php
@@ -46,7 +46,7 @@
    * {@inheritdoc}
    */
   public function retranslate(EntityInterface $entity, $langcode = NULL) {
-    $updated_langcode = !empty($langcode) ? $langcode : $entity->language()->id;
+    $updated_langcode = !empty($langcode) ? $langcode : $entity->language()->getId();
     $translations = $entity->getTranslationLanguages();
     foreach ($translations as $langcode => $language) {
       $entity->translation[$langcode]['outdated'] = $langcode != $updated_langcode;
@@ -82,7 +82,7 @@
   public function entityFormAlter(array &$form, array &$form_state, EntityInterface $entity) {
     $form_controller = content_translation_form_controller($form_state);
     $form_langcode = $form_controller->getFormLangcode($form_state);
-    $entity_langcode = $entity->getUntranslated()->language()->id;
+    $entity_langcode = $entity->getUntranslated()->language()->getId();
     $source_langcode = $this->getSourceLangcode($form_state);
 
     $new_translation = !empty($source_langcode);
diff -u b/core/modules/locale/lib/Drupal/locale/Tests/LocalePathTest.php b/core/modules/locale/lib/Drupal/locale/Tests/LocalePathTest.php
--- b/core/modules/locale/lib/Drupal/locale/Tests/LocalePathTest.php
+++ b/core/modules/locale/lib/Drupal/locale/Tests/LocalePathTest.php
@@ -124,7 +124,7 @@
     $edit = array(
       'source'   => 'node/' . $first_node->id(),
       'alias'    => $custom_path,
-      'langcode' => $first_node->language()->id,
+      'langcode' => $first_node->language()->getId(),
     );
     $this->container->get('path.alias_storage')->save($edit['source'], $edit['alias'], $edit['langcode']);
 
@@ -132,7 +132,7 @@
     $edit = array(
       'source'   => 'node/' . $second_node->id(),
       'alias'    => $custom_path,
-      'langcode' => $second_node->language()->id,
+      'langcode' => $second_node->language()->getId(),
     );
     $this->container->get('path.alias_storage')->save($edit['source'], $edit['alias'], $edit['langcode']);
 
diff -u b/core/modules/migrate_drupal/lib/Drupal/migrate_drupal/Tests/d6/MigrateAggregatorFeedTest.php b/core/modules/migrate_drupal/lib/Drupal/migrate_drupal/Tests/d6/MigrateAggregatorFeedTest.php
--- b/core/modules/migrate_drupal/lib/Drupal/migrate_drupal/Tests/d6/MigrateAggregatorFeedTest.php
+++ b/core/modules/migrate_drupal/lib/Drupal/migrate_drupal/Tests/d6/MigrateAggregatorFeedTest.php
@@ -49,7 +49,7 @@
     $feed = entity_load('aggregator_feed', 5);
     $this->assertNotNull($feed->uuid());
     $this->assertEqual($feed->title->value, 'Know Your Meme');
-    $this->assertEqual($feed->language()->id, LanguageInterface::LANGCODE_NOT_SPECIFIED);
+    $this->assertEqual($feed->language()->getId(), LanguageInterface::LANGCODE_NOT_SPECIFIED);
     $this->assertEqual($feed->url->value, 'http://knowyourmeme.com/newsfeed.rss');
     $this->assertEqual($feed->refresh->value, 900);
     $this->assertEqual($feed->checked->value, 1387659487);
diff -u b/core/modules/migrate_drupal/lib/Drupal/migrate_drupal/Tests/d6/MigrateAggregatorItemTest.php b/core/modules/migrate_drupal/lib/Drupal/migrate_drupal/Tests/d6/MigrateAggregatorItemTest.php
--- b/core/modules/migrate_drupal/lib/Drupal/migrate_drupal/Tests/d6/MigrateAggregatorItemTest.php
+++ b/core/modules/migrate_drupal/lib/Drupal/migrate_drupal/Tests/d6/MigrateAggregatorItemTest.php
@@ -76,7 +76,7 @@
     $this->assertEqual($item->getDescription(), "<h2 id='new'>What's new with Drupal 8?</h2>");
     $this->assertEqual($item->getLink(), 'https://groups.drupal.org/node/395218');
     $this->assertEqual($item->getPostedTime(), 1389297196);
-    $this->assertEqual($item->language()->id, LanguageInterface::LANGCODE_NOT_SPECIFIED);
+    $this->assertEqual($item->language()->getId(), LanguageInterface::LANGCODE_NOT_SPECIFIED);
     $this->assertEqual($item->getGuid(), '395218 at https://groups.drupal.org');
 
   }
diff -u b/core/modules/migrate_drupal/lib/Drupal/migrate_drupal/Tests/d6/MigrateCommentTest.php b/core/modules/migrate_drupal/lib/Drupal/migrate_drupal/Tests/d6/MigrateCommentTest.php
--- b/core/modules/migrate_drupal/lib/Drupal/migrate_drupal/Tests/d6/MigrateCommentTest.php
+++ b/core/modules/migrate_drupal/lib/Drupal/migrate_drupal/Tests/d6/MigrateCommentTest.php
@@ -76,7 +76,7 @@
     $this->assertEqual(0, $comment->pid->value);
     $this->assertEqual(1, $comment->entity_id->value);
     $this->assertEqual('node', $comment->entity_type->value);
-    $this->assertEqual(LanguageInterface::LANGCODE_NOT_SPECIFIED, $comment->language()->id);
+    $this->assertEqual(LanguageInterface::LANGCODE_NOT_SPECIFIED, $comment->language()->getId());
 
     $comment = entity_load('comment', 2);
     $this->assertEqual('The response to the second comment.', $comment->subject->value);
diff -u b/core/modules/migrate_drupal/lib/Drupal/migrate_drupal/Tests/d6/MigrateCustomBlockTest.php b/core/modules/migrate_drupal/lib/Drupal/migrate_drupal/Tests/d6/MigrateCustomBlockTest.php
--- b/core/modules/migrate_drupal/lib/Drupal/migrate_drupal/Tests/d6/MigrateCustomBlockTest.php
+++ b/core/modules/migrate_drupal/lib/Drupal/migrate_drupal/Tests/d6/MigrateCustomBlockTest.php
@@ -59,7 +59,7 @@
     $this->assertEqual('My block 1', $block->label());
     $this->assertEqual(1, $block->getRevisionId());
     $this->assertTrue(REQUEST_TIME <= $block->getChangedTime() && $block->getChangedTime() <= time());
-    $this->assertEqual(LanguageInterface::LANGCODE_NOT_SPECIFIED, $block->language()->id);
+    $this->assertEqual(LanguageInterface::LANGCODE_NOT_SPECIFIED, $block->language()->getId());
     $this->assertEqual('<h3>My custom block body</h3>', $block->body->value);
     $this->assertEqual('full_html', $block->body->format);
   }
diff -u b/core/modules/node/lib/Drupal/node/Entity/Node.php b/core/modules/node/lib/Drupal/node/Entity/Node.php
--- b/core/modules/node/lib/Drupal/node/Entity/Node.php
+++ b/core/modules/node/lib/Drupal/node/Entity/Node.php
@@ -155,7 +155,7 @@
    * {@inheritdoc}
    */
   public function prepareLangcode() {
-    $langcode = $this->language()->id;
+    $langcode = $this->language()->getId();
     // If the Language module is enabled, try to use the language from content
     // negotiation.
     if (\Drupal::moduleHandler()->moduleExists('language')) {
diff -u b/core/modules/node/lib/Drupal/node/NodeForm.php b/core/modules/node/lib/Drupal/node/NodeForm.php
--- b/core/modules/node/lib/Drupal/node/NodeForm.php
+++ b/core/modules/node/lib/Drupal/node/NodeForm.php
@@ -89,7 +89,7 @@
     $form['langcode'] = array(
       '#title' => t('Language'),
       '#type' => 'language_select',
-      '#default_value' => $node->getUntranslated()->language()->id,
+      '#default_value' => $node->getUntranslated()->language()->getId(),
       '#languages' => LanguageInterface::STATE_ALL,
       '#access' => isset($language_configuration['language_show']) && $language_configuration['language_show'],
     );
diff -u b/core/modules/node/lib/Drupal/node/NodeListBuilder.php b/core/modules/node/lib/Drupal/node/NodeListBuilder.php
--- b/core/modules/node/lib/Drupal/node/NodeListBuilder.php
+++ b/core/modules/node/lib/Drupal/node/NodeListBuilder.php
@@ -96,7 +96,7 @@
       '#theme' => 'mark',
       '#mark_type' => node_mark($entity->id(), $entity->getChangedTime()),
     );
-    $langcode = $entity->language()->id;
+    $langcode = $entity->language()->getId();
     $uri = $entity->urlInfo();
     $options = $uri->getOptions();
     $options += ($langcode != LanguageInterface::LANGCODE_NOT_SPECIFIED && isset($languages[$langcode]) ? array('language' => $languages[$langcode]) : array());
diff -u b/core/modules/node/lib/Drupal/node/Plugin/Search/NodeSearch.php b/core/modules/node/lib/Drupal/node/Plugin/Search/NodeSearch.php
--- b/core/modules/node/lib/Drupal/node/Plugin/Search/NodeSearch.php
+++ b/core/modules/node/lib/Drupal/node/Plugin/Search/NodeSearch.php
@@ -287,7 +287,7 @@
         'extra' => $extra,
         'score' => $item->calculated_score,
         'snippet' => search_excerpt($keys, $node->rendered, $item->langcode),
-        'langcode' => $node->language()->id,
+        'langcode' => $node->language()->getId(),
       );
     }
     return $results;
diff -u b/core/modules/node/lib/Drupal/node/Tests/NodeAccessLanguageTest.php b/core/modules/node/lib/Drupal/node/Tests/NodeAccessLanguageTest.php
--- b/core/modules/node/lib/Drupal/node/Tests/NodeAccessLanguageTest.php
+++ b/core/modules/node/lib/Drupal/node/Tests/NodeAccessLanguageTest.php
@@ -65,7 +65,7 @@
     // Creating a public node with langcode Hungarian, will be saved as the
     // fallback in node access table.
     $node_public_hu = $this->drupalCreateNode(array('body' => array(array()), 'langcode' => 'hu', 'private' => FALSE));
-    $this->assertTrue($node_public_hu->language()->id == 'hu', 'Node created as Hungarian.');
+    $this->assertTrue($node_public_hu->language()->getId() == 'hu', 'Node created as Hungarian.');
 
     // Tests the default access is provided for the public Hungarian node.
     $this->assertNodeAccess($expected_node_access, $node_public_hu, $web_user);
@@ -82,7 +82,7 @@
     // Creating a public node with no special langcode, like when no language
     // module enabled.
     $node_public_no_language = $this->drupalCreateNode(array('private' => FALSE));
-    $this->assertTrue($node_public_no_language->language()->id == LanguageInterface::LANGCODE_NOT_SPECIFIED, 'Node created with not specified language.');
+    $this->assertTrue($node_public_no_language->language()->getId() == LanguageInterface::LANGCODE_NOT_SPECIFIED, 'Node created with not specified language.');
 
     // Tests that access is granted if requested with no language.
     $this->assertNodeAccess($expected_node_access, $node_public_no_language, $web_user);
@@ -100,7 +100,7 @@
     \Drupal::entityManager()->getAccessController('node')->resetCache();
     \Drupal::state()->set('node_access_test_secret_catalan', 1);
     $node_public_ca = $this->drupalCreateNode(array('body' => array(array()), 'langcode' => 'ca', 'private' => FALSE));
-    $this->assertTrue($node_public_ca->language()->id == 'ca', 'Node created as Catalan.');
+    $this->assertTrue($node_public_ca->language()->getId() == 'ca', 'Node created as Catalan.');
 
     // Tests that access is granted if requested with no language.
     $this->assertNodeAccess($expected_node_access, $node_public_no_language, $web_user);
@@ -155,7 +155,7 @@
     // Creating a private node with langcode Hungarian, will be saved as the
     // fallback in node access table.
     $node_private_hu = $this->drupalCreateNode(array('body' => array(array()), 'langcode' => 'hu', 'private' => TRUE));
-    $this->assertTrue($node_private_hu->language()->id == 'hu', 'Node created as Hungarian.');
+    $this->assertTrue($node_private_hu->language()->getId() == 'hu', 'Node created as Hungarian.');
 
     // Tests the default access is not provided for the private Hungarian node.
     $this->assertNodeAccess($expected_node_access_no_access, $node_private_hu, $web_user);
@@ -172,7 +172,7 @@
     // Creating a private node with no special langcode, like when no language
     // module enabled.
     $node_private_no_language = $this->drupalCreateNode(array('private' => TRUE));
-    $this->assertTrue($node_private_no_language->language()->id == LanguageInterface::LANGCODE_NOT_SPECIFIED, 'Node created with not specified language.');
+    $this->assertTrue($node_private_no_language->language()->getId() == LanguageInterface::LANGCODE_NOT_SPECIFIED, 'Node created with not specified language.');
 
     // Tests that access is not granted if requested with no language.
     $this->assertNodeAccess($expected_node_access_no_access, $node_private_no_language, $web_user);
@@ -203,7 +203,7 @@
     // node_access_test_secret_catalan flag works.
     $private_ca_user = $this->drupalCreateUser(array('access content', 'node test view'));
     $node_private_ca = $this->drupalCreateNode(array('body' => array(array()), 'langcode' => 'ca', 'private' => TRUE));
-    $this->assertTrue($node_private_ca->language()->id == 'ca', 'Node created as Catalan.');
+    $this->assertTrue($node_private_ca->language()->getId() == 'ca', 'Node created as Catalan.');
 
     // Tests that Catalan is still not accessible to either user.
     $this->assertNodeAccess($expected_node_access_no_access, $node_private_ca, $web_user, 'ca');
@@ -235,17 +235,17 @@
     // Creating a private node with langcode Hungarian, will be saved as
     // the fallback in node access table.
     $node_private = $this->drupalCreateNode(array('body' => array(array()), 'langcode' => 'hu', 'private' => TRUE));
-    $this->assertTrue($node_private->language()->id == 'hu', 'Node created as Hungarian.');
+    $this->assertTrue($node_private->language()->getId() == 'hu', 'Node created as Hungarian.');
 
     // Creating a public node with langcode Hungarian, will be saved as
     // the fallback in node access table.
     $node_public = $this->drupalCreateNode(array('body' => array(array()), 'langcode' => 'hu', 'private' => FALSE));
-    $this->assertTrue($node_public->language()->id == 'hu', 'Node created as Hungarian.');
+    $this->assertTrue($node_public->language()->getId() == 'hu', 'Node created as Hungarian.');
 
     // Creating a public node with no special langcode, like when no language
     // module enabled.
     $node_no_language = $this->drupalCreateNode(array('private' => FALSE));
-    $this->assertTrue($node_no_language->language()->id == LanguageInterface::LANGCODE_NOT_SPECIFIED, 'Node created with not specified language.');
+    $this->assertTrue($node_no_language->language()->getId() == LanguageInterface::LANGCODE_NOT_SPECIFIED, 'Node created with not specified language.');
 
     // Query the nodes table as the web user with the node access tag and no
     // specific langcode.
diff -u b/core/modules/node/lib/Drupal/node/Tests/NodeFieldMultilingualTestCase.php b/core/modules/node/lib/Drupal/node/Tests/NodeFieldMultilingualTestCase.php
--- b/core/modules/node/lib/Drupal/node/Tests/NodeFieldMultilingualTestCase.php
+++ b/core/modules/node/lib/Drupal/node/Tests/NodeFieldMultilingualTestCase.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\node\Tests;
 
+use Drupal\Core\Language\LanguageInterface;
 use Drupal\language\Plugin\LanguageNegotiation\LanguageNegotiationUrl;
 use Drupal\simpletest\WebTestBase;
 use Drupal\Core\Language\Language;
@@ -85,7 +86,7 @@
     // Check that the node exists in the database.
     $node = $this->drupalGetNodeByTitle($edit[$title_key]);
     $this->assertTrue($node, 'Node found in database.');
-    $this->assertTrue($node->language()->id == $langcode && $node->body->value == $body_value, 'Field language correctly set.');
+    $this->assertTrue($node->language()->getId() == $langcode && $node->body->value == $body_value, 'Field language correctly set.');
 
     // Change node language.
     $langcode = 'it';
@@ -97,7 +98,7 @@
     $this->drupalPostForm(NULL, $edit, t('Save'));
     $node = $this->drupalGetNodeByTitle($edit[$title_key], TRUE);
     $this->assertTrue($node, 'Node found in database.');
-    $this->assertTrue($node->language()->id == $langcode && $node->body->value == $body_value, 'Field language correctly changed.');
+    $this->assertTrue($node->language()->getId() == $langcode && $node->body->value == $body_value, 'Field language correctly changed.');
 
     // Enable content language URL detection.
     $this->container->get('language_negotiator')->saveConfiguration(LanguageInterface::TYPE_CONTENT, array(LanguageNegotiationUrl::METHOD_ID => 0));
diff -u b/core/modules/node/node.tokens.inc b/core/modules/node/node.tokens.inc
--- b/core/modules/node/node.tokens.inc
+++ b/core/modules/node/node.tokens.inc
@@ -134,7 +134,7 @@
           if (($items = $translation->get('body')) && !$items->isEmpty()) {
             $item = $items[0];
             $instance = field_info_instance('node', 'body', $node->getType());
-            $field_langcode = $translation->language()->id;
+            $field_langcode = $translation->language()->getId();
             // If the summary was requested and is not empty, use it.
             if ($name == 'summary' && !empty($item->summary)) {
               $output = $sanitize ? $item->summary_processed : $item->summary;
@@ -165,7 +165,7 @@
           break;
 
         case 'langcode':
-          $replacements[$original] = $sanitize ? check_plain($node->language()->id) : $node->language()->id;
+          $replacements[$original] = $sanitize ? check_plain($node->language()->getId()) : $node->language()->getId();
           break;
 
         case 'url':
diff -u b/core/modules/shortcut/src/ShortcutForm.php b/core/modules/shortcut/src/ShortcutForm.php
--- b/core/modules/shortcut/src/ShortcutForm.php
+++ b/core/modules/shortcut/src/ShortcutForm.php
@@ -40,7 +40,7 @@
     $form['langcode'] = array(
       '#title' => t('Language'),
       '#type' => 'language_select',
-      '#default_value' => $this->entity->getUntranslated()->language()->id,
+      '#default_value' => $this->entity->getUntranslated()->language()->getId(),
       '#languages' => LanguageInterface::STATE_ALL,
     );
 
reverted:
--- b/core/modules/simpletest/lib/Drupal/simpletest/DrupalUnitTestBase.php
+++ a/core/modules/simpletest/lib/Drupal/simpletest/DrupalUnitTestBase.php
@@ -10,7 +10,7 @@
 use Drupal\Core\DependencyInjection\ContainerBuilder;
 use Drupal\Core\DrupalKernel;
 use Drupal\Core\KeyValueStore\KeyValueMemoryFactory;
+use Drupal\Core\Language\Language;
-use Drupal\Core\Language\LanguageInterface;
 use Symfony\Component\DependencyInjection\Reference;
 use Drupal\Core\Database\Database;
 use Symfony\Component\HttpFoundation\Request;
@@ -222,7 +222,7 @@
     $this->container = $container;
 
     // Set the default language on the minimal container.
+    $this->container->setParameter('language.default_values', Language::$defaultValues);
-    $this->container->setParameter('language.default_values', LanguageInterface::$defaultValues);
 
     $container->register('lock', 'Drupal\Core\Lock\NullLockBackend');
     $container->register('cache_factory', 'Drupal\Core\Cache\MemoryBackendFactory');
reverted:
--- b/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php
+++ a/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php
@@ -16,7 +16,7 @@
 use Drupal\Core\Database\ConnectionNotDefinedException;
 use Drupal\Core\Config\StorageInterface;
 use Drupal\Core\DrupalKernel;
+use Drupal\Core\Language\Language;
-use Drupal\Core\Language\LanguageInterface;
 use Drupal\Core\Session\AccountProxy;
 use Drupal\Core\Session\AnonymousUserSession;
 use Drupal\Core\Site\Settings;
@@ -1071,7 +1071,7 @@
     $this->container = new ContainerBuilder();
 
     // @todo Remove this once this class has no calls to t() and format_plural()
+    $this->container->setParameter('language.default_values', Language::$defaultValues);
-    $this->container->setParameter('language.default_values', LanguageInterface::$defaultValues);
     $this->container->register('language.default', 'Drupal\Core\Language\LanguageDefault')
       ->addArgument('%language.default_values%');
     $this->container->register('language_manager', 'Drupal\Core\Language\LanguageManager')
diff -u b/core/modules/system/lib/Drupal/system/Tests/Entity/EntityTranslationFormTest.php b/core/modules/system/lib/Drupal/system/Tests/Entity/EntityTranslationFormTest.php
--- b/core/modules/system/lib/Drupal/system/Tests/Entity/EntityTranslationFormTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Entity/EntityTranslationFormTest.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\system\Tests\Entity;
 
+use Drupal\Core\Language\LanguageInterface;
 use Drupal\simpletest\WebTestBase;
 use Drupal\Core\Language\Language;
 
@@ -68,12 +69,12 @@
     $this->drupalPostForm(NULL, $edit, t('Save'));
 
     $node = $this->drupalGetNodeByTitle($edit['title[0][value]']);
-    $this->assertTrue($node->language()->id == $form_langcode, 'Form language is the same as the entity language.');
+    $this->assertTrue($node->language()->getId() == $form_langcode, 'Form language is the same as the entity language.');
 
     // Edit the node and test the form language.
     $this->drupalGet($this->langcodes[0] . '/node/' . $node->id() . '/edit');
     $form_langcode = \Drupal::state()->get('entity_test.form_langcode') ?: FALSE;
-    $this->assertTrue($node->language()->id == $form_langcode, 'Form language is the same as the entity language.');
+    $this->assertTrue($node->language()->getId() == $form_langcode, 'Form language is the same as the entity language.');
 
     // Explicitly set form langcode.
     $langcode = $this->langcodes[0];
diff -u b/core/modules/system/lib/Drupal/system/Tests/Entity/EntityTranslationTest.php b/core/modules/system/lib/Drupal/system/Tests/Entity/EntityTranslationTest.php
--- b/core/modules/system/lib/Drupal/system/Tests/Entity/EntityTranslationTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Entity/EntityTranslationTest.php
@@ -44,7 +44,7 @@
       'name' => 'test',
       'user_id' => $this->container->get('current_user')->id(),
     ));
-    $this->assertEqual($entity->language()->id, LanguageInterface::LANGCODE_NOT_SPECIFIED, format_string('%entity_type: Entity language not specified.', array('%entity_type' => $entity_type)));
+    $this->assertEqual($entity->language()->getId(), LanguageInterface::LANGCODE_NOT_SPECIFIED, format_string('%entity_type: Entity language not specified.', array('%entity_type' => $entity_type)));
     $this->assertFalse($entity->getTranslationLanguages(FALSE), format_string('%entity_type: No translations are available', array('%entity_type' => $entity_type)));
 
     // Set the value in default language.
@@ -152,7 +152,7 @@
     $entity = entity_create($entity_type, array('name' => $name, 'user_id' => $uid));
     $entity->save();
     $entity = entity_load($entity_type, $entity->id());
-    $default_langcode = $entity->language()->id;
+    $default_langcode = $entity->language()->getId();
     $this->assertEqual($default_langcode, LanguageInterface::LANGCODE_NOT_SPECIFIED, format_string('%entity_type: Entity created as language neutral.', array('%entity_type' => $entity_type)));
     $field = $entity->getTranslation(LanguageInterface::LANGCODE_DEFAULT)->get('name');
     $this->assertEqual($name, $field->value, format_string('%entity_type: The entity name has been correctly stored as language neutral.', array('%entity_type' => $entity_type)));
@@ -172,7 +172,7 @@
     $entity = entity_create($entity_type, array('name' => $name, 'user_id' => $uid, 'langcode' => $langcode));
     $entity->save();
     $entity = entity_load($entity_type, $entity->id());
-    $default_langcode = $entity->language()->id;
+    $default_langcode = $entity->language()->getId();
     $this->assertEqual($default_langcode, $langcode, format_string('%entity_type: Entity created as language specific.', array('%entity_type' => $entity_type)));
     $field = $entity->getTranslation($langcode)->get('name');
     $this->assertEqual($name, $field->value, format_string('%entity_type: The entity name has been correctly stored as a language-aware property.', array('%entity_type' => $entity_type)));
@@ -221,7 +221,7 @@
       );
       $field = $entity->getTranslation($langcode)->get('name');
       $this->assertEqual($properties[$langcode]['name'][0], $field->value, format_string('%entity_type: The entity name has been correctly stored for language %langcode.', $args));
-      $field_langcode = ($langcode == $entity->language()->id) ? $default_langcode : $langcode;
+      $field_langcode = ($langcode == $entity->language()->getId()) ? $default_langcode : $langcode;
       $this->assertEqual($field_langcode, $field->getLangcode(), format_string('%entity_type: The field object has the expected langcode  %langcode.', $args));
       $this->assertEqual($properties[$langcode]['user_id'][0], $entity->getTranslation($langcode)->get('user_id')->target_id, format_string('%entity_type: The entity author has been correctly stored for language %langcode.', $args));
     }
@@ -320,8 +320,8 @@
     $translation = $entity->addTranslation($langcode);
     $this->assertNotIdentical($entity, $translation, 'The entity and the translation object differ from one another.');
     $this->assertTrue($entity->hasTranslation($langcode), 'The new translation exists.');
-    $this->assertEqual($translation->language()->id, $langcode, 'The translation language matches the specified one.');
-    $this->assertEqual($translation->getUntranslated()->language()->id, $default_langcode, 'The original language can still be retrieved.');
+    $this->assertEqual($translation->language()->getId(), $langcode, 'The translation language matches the specified one.');
+    $this->assertEqual($translation->getUntranslated()->language()->getId(), $default_langcode, 'The original language can still be retrieved.');
     $translation->name->value = $name_translated;
     $this->assertEqual($entity->name->value, $name, 'The original name is retained after setting a translated value.');
     $entity->name->value = $name;
@@ -335,16 +335,16 @@
 
     // Check that after loading an entity the language is the default one.
     $entity = $this->reloadEntity($entity);
-    $this->assertEqual($entity->language()->id, $default_langcode, 'The loaded entity is the original one.');
+    $this->assertEqual($entity->language()->getId(), $default_langcode, 'The loaded entity is the original one.');
 
     // Add another translation and check that everything works as expected. A
     // new translation object can be obtained also by just specifying a valid
     // language.
     $langcode2 = $this->langcodes[2];
     $translation = $entity->getTranslation($langcode2);
-    $value = $entity !== $translation && $translation->language()->id == $langcode2 && $entity->hasTranslation($langcode2);
+    $value = $entity !== $translation && $translation->language()->getId() == $langcode2 && $entity->hasTranslation($langcode2);
     $this->assertTrue($value, 'A new translation object can be obtained also by specifying a valid language.');
-    $this->assertEqual($entity->language()->id, $default_langcode, 'The original language has been preserved.');
+    $this->assertEqual($entity->language()->getId(), $default_langcode, 'The original language has been preserved.');
     $translation->save();
     $hooks = $this->getHooksInfo();
     $this->assertEqual($hooks['entity_translation_insert'], $langcode2, 'The generic entity translation insertion hook has fired.');
@@ -472,21 +472,21 @@
     // Check that retrieveing the current translation works as expected.
     $entity = $this->reloadEntity($entity);
     $translation = $this->entityManager->getTranslationFromContext($entity, $langcode2);
-    $this->assertEqual($translation->language()->id, $default_langcode, 'The current translation language matches the expected one.');
+    $this->assertEqual($translation->language()->getId(), $default_langcode, 'The current translation language matches the expected one.');
 
     // Check that language fallback respects language weight by default.
     $languages = $this->languageManager->getLanguages();
     $languages[$langcode]->weight = -1;
     language_save($languages[$langcode]);
     $translation = $this->entityManager->getTranslationFromContext($entity, $langcode2);
-    $this->assertEqual($translation->language()->id, $langcode, 'The current translation language matches the expected one.');
+    $this->assertEqual($translation->language()->getId(), $langcode, 'The current translation language matches the expected one.');
 
     // Check that the current translation is properly returned.
     $translation = $this->entityManager->getTranslationFromContext($entity);
-    $this->assertEqual($langcode, $translation->language()->id, 'The current translation language matches the topmost language fallback candidate.');
+    $this->assertEqual($langcode, $translation->language()->getId(), 'The current translation language matches the topmost language fallback candidate.');
     $entity->addTranslation($current_langcode, $values[$current_langcode]);
     $translation = $this->entityManager->getTranslationFromContext($entity);
-    $this->assertEqual($current_langcode, $translation->language()->id, 'The current translation language matches the current language.');
+    $this->assertEqual($current_langcode, $translation->language()->getId(), 'The current translation language matches the current language.');
 
     // Check that if the entity has no translation no fallback is applied.
     $entity2 = $controller->create(array('langcode' => $default_langcode));
diff -u b/core/modules/system/lib/Drupal/system/Tests/Entity/FieldTranslationSqlStorageTest.php b/core/modules/system/lib/Drupal/system/Tests/Entity/FieldTranslationSqlStorageTest.php
--- b/core/modules/system/lib/Drupal/system/Tests/Entity/FieldTranslationSqlStorageTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Entity/FieldTranslationSqlStorageTest.php
@@ -87,7 +87,7 @@
     $status = TRUE;
     $entity_type = $entity->getEntityTypeId();
     $id = $entity->id();
-    $langcode = $entity->getUntranslated()->language()->id;
+    $langcode = $entity->getUntranslated()->language()->getId();
     $fields = array($this->field_name, $this->untranslatable_field_name);
 
     foreach ($fields as $field_name) {
diff -u b/core/modules/system/tests/modules/entity_test/lib/Drupal/entity_test/EntityTestForm.php b/core/modules/system/tests/modules/entity_test/lib/Drupal/entity_test/EntityTestForm.php
--- b/core/modules/system/tests/modules/entity_test/lib/Drupal/entity_test/EntityTestForm.php
+++ b/core/modules/system/tests/modules/entity_test/lib/Drupal/entity_test/EntityTestForm.php
@@ -44,7 +44,7 @@
     $form['langcode'] = array(
       '#title' => t('Language'),
       '#type' => 'language_select',
-      '#default_value' => $entity->getUntranslated()->language()->id,
+      '#default_value' => $entity->getUntranslated()->language()->getId(),
       '#languages' => LanguageInterface::STATE_ALL,
     );
 
diff -u b/core/modules/taxonomy/lib/Drupal/taxonomy/TermForm.php b/core/modules/taxonomy/lib/Drupal/taxonomy/TermForm.php
--- b/core/modules/taxonomy/lib/Drupal/taxonomy/TermForm.php
+++ b/core/modules/taxonomy/lib/Drupal/taxonomy/TermForm.php
@@ -33,7 +33,7 @@
       '#type' => 'language_select',
       '#title' => $this->t('Language'),
       '#languages' => LanguageInterface::STATE_ALL,
-      '#default_value' => $term->getUntranslated()->language()->id,
+      '#default_value' => $term->getUntranslated()->language()->getId(),
       '#access' => !empty($language_configuration['language_show']),
     );
 
only in patch2:
unchanged:
--- a/core/lib/Drupal/Core/Entity/ContentEntityForm.php
+++ b/core/lib/Drupal/Core/Entity/ContentEntityForm.php
@@ -90,7 +90,7 @@ public function getFormLangcode(array &$form_state) {
       // Imply a 'view' operation to ensure users edit entities in the same
       // language they are displayed. This allows to keep contextual editing
       // working also for multilingual entities.
-      $form_state['langcode'] = $this->entityManager->getTranslationFromContext($this->entity)->language()->id;
+      $form_state['langcode'] = $this->entityManager->getTranslationFromContext($this->entity)->language()->getId();
     }
     return $form_state['langcode'];
   }
@@ -99,7 +99,7 @@ public function getFormLangcode(array &$form_state) {
    * {@inheritdoc}
    */
   public function isDefaultFormLangcode(array $form_state) {
-    return $this->getFormLangcode($form_state) == $this->entity->getUntranslated()->language()->id;
+    return $this->getFormLangcode($form_state) == $this->entity->getUntranslated()->language()->getId();
   }
 
   /**
only in patch2:
unchanged:
--- a/core/lib/Drupal/Core/Entity/EntityForm.php
+++ b/core/lib/Drupal/Core/Entity/EntityForm.php
@@ -145,7 +145,7 @@ public function form(array $form, array &$form_state) {
       // new entities.
       $form['langcode'] = array(
         '#type' => 'value',
-        '#value' => !$entity->isNew() ? $entity->language()->id : language_default()->id,
+        '#value' => !$entity->isNew() ? $entity->language()->getId() : language_default()->getId(),
       );
     }
     return $form;
@@ -287,7 +287,7 @@ public function save(array $form, array &$form_state) {
    * {@inheritdoc}
    */
   public function getFormLangcode(array &$form_state) {
-    return $this->entity->language()->id;
+    return $this->entity->language()->getId();
   }
 
   /**
only in patch2:
unchanged:
--- a/core/modules/aggregator/lib/Drupal/aggregator/Plugin/aggregator/processor/DefaultProcessor.php
+++ b/core/modules/aggregator/lib/Drupal/aggregator/Plugin/aggregator/processor/DefaultProcessor.php
@@ -190,7 +190,7 @@ public function process(FeedInterface $feed) {
         $entry = reset($entry);
       }
       else {
-        $entry = entity_create('aggregator_item', array('langcode' => $feed->language()->id));
+        $entry = entity_create('aggregator_item', array('langcode' => $feed->language()->getId()));
       }
       if ($item['timestamp']) {
         $entry->setPostedTime($item['timestamp']);
only in patch2:
unchanged:
--- a/core/modules/content_translation/lib/Drupal/content_translation/FieldTranslationSynchronizer.php
+++ b/core/modules/content_translation/lib/Drupal/content_translation/FieldTranslationSynchronizer.php
@@ -50,7 +50,7 @@ public function synchronizeFields(ContentEntityInterface $entity, $sync_langcode
     // If the entity language is being changed there is nothing to synchronize.
     $entity_type = $entity->getEntityTypeId();
     $entity_unchanged = isset($entity->original) ? $entity->original : $this->entityManager->getStorage($entity_type)->loadUnchanged($entity->id());
-    if ($entity->getUntranslated()->language()->id != $entity_unchanged->getUntranslated()->language()->id) {
+    if ($entity->getUntranslated()->language()->getId() != $entity_unchanged->getUntranslated()->language()->getId()) {
       return;
     }
 
only in patch2:
unchanged:
--- a/core/modules/field/lib/Drupal/field/Entity/FieldInstanceConfig.php
+++ b/core/modules/field/lib/Drupal/field/Entity/FieldInstanceConfig.php
@@ -603,7 +603,7 @@ public function isMultiple() {
   public function getDefaultValue(EntityInterface $entity) {
     if (!empty($this->default_value_function)) {
       $function = $this->default_value_function;
-      return $function($entity, $this->getField(), $this, $entity->language()->id);
+      return $function($entity, $this->getField(), $this, $entity->language()->getId());
     }
     elseif (!empty($this->default_value)) {
       return $this->default_value;
only in patch2:
unchanged:
--- a/core/modules/field/lib/Drupal/field/Tests/TranslationTest.php
+++ b/core/modules/field/lib/Drupal/field/Tests/TranslationTest.php
@@ -176,7 +176,7 @@ function testTranslatableFieldSaveLoad() {
 
     // @todo Test every translation once the Entity Translation API allows for
     //   multilingual defaults.
-    $langcode = $entity->language()->id;
+    $langcode = $entity->language()->getId();
     $this->assertEqual($entity->getTranslation($langcode)->{$field_name_default}->getValue(), $instance->default_value, format_string('Default value correctly populated for language %language.', array('%language' => $langcode)));
 
     // Check that explicit empty values are not overridden with default values.
only in patch2:
unchanged:
--- a/core/modules/field/tests/modules/field_test/field_test.module
+++ b/core/modules/field/tests/modules/field_test/field_test.module
@@ -108,7 +108,7 @@ function field_test_entity_display_build_alter(&$output, $context) {
   }
 
   if (isset($output['test_field'])) {
-    $output['test_field'][] = array('#markup' => 'entity language is ' . $context['entity']->language()->id);
+    $output['test_field'][] = array('#markup' => 'entity language is ' . $context['entity']->language()->getId());
   }
 }
 
only in patch2:
unchanged:
--- a/core/modules/node/lib/Drupal/node/Access/NodeRevisionAccessCheck.php
+++ b/core/modules/node/lib/Drupal/node/Access/NodeRevisionAccessCheck.php
@@ -119,7 +119,7 @@ public function checkAccess(NodeInterface $node, AccountInterface $account, $op
 
     // If no language code was provided, default to the node revision's langcode.
     if (empty($langcode)) {
-      $langcode = $node->language()->id;
+      $langcode = $node->language()->getId();
     }
 
     // Statically cache access by revision ID, language code, user account ID,
only in patch2:
unchanged:
--- a/core/modules/node/lib/Drupal/node/NodeGrantDatabaseStorage.php
+++ b/core/modules/node/lib/Drupal/node/NodeGrantDatabaseStorage.php
@@ -190,7 +190,7 @@ public function write(NodeInterface $node, array $grants, $realm = NULL, $delete
             $grant['nid'] = $node->id();
             $grant['langcode'] = $grant_langcode;
             // The record with the original langcode is used as the fallback.
-            if ($grant['langcode'] == $node->language()->id) {
+            if ($grant['langcode'] == $node->language()->getId()) {
               $grant['fallback'] = 1;
             }
             else {
only in patch2:
unchanged:
--- a/core/modules/node/lib/Drupal/node/Tests/NodeLastChangedTest.php
+++ b/core/modules/node/lib/Drupal/node/Tests/NodeLastChangedTest.php
@@ -49,7 +49,7 @@ function testNodeLastChanged() {
     $changed_timestamp = node_last_changed($node->id());
     $this->assertEqual($changed_timestamp, $node->getChangedTime(), 'Expected last changed timestamp returned.');
 
-    $changed_timestamp = node_last_changed($node->id(), $node->language()->id);
+    $changed_timestamp = node_last_changed($node->id(), $node->language()->getId());
     $this->assertEqual($changed_timestamp, $node->getChangedTime(), 'Expected last changed timestamp returned.');
   }
 }
only in patch2:
unchanged:
--- a/core/modules/node/lib/Drupal/node/Tests/NodeTokenReplaceTest.php
+++ b/core/modules/node/lib/Drupal/node/Tests/NodeTokenReplaceTest.php
@@ -76,7 +76,7 @@ function testNodeTokenReplacement() {
     $tests['[node:title]'] = check_plain($node->getTitle());
     $tests['[node:body]'] = $node->body->processed;
     $tests['[node:summary]'] = $node->body->summary_processed;
-    $tests['[node:langcode]'] = check_plain($node->language()->id);
+    $tests['[node:langcode]'] = check_plain($node->language()->getId());
     $tests['[node:url]'] = url('node/' . $node->id(), $url_options);
     $tests['[node:edit-url]'] = url('node/' . $node->id() . '/edit', $url_options);
     $tests['[node:author]'] = String::checkPlain($account->getUsername());
@@ -97,7 +97,7 @@ function testNodeTokenReplacement() {
     $tests['[node:title]'] = $node->getTitle();
     $tests['[node:body]'] = $node->body->value;
     $tests['[node:summary]'] = $node->body->summary;
-    $tests['[node:langcode]'] = $node->language()->id;
+    $tests['[node:langcode]'] = $node->language()->getId();
     $tests['[node:author:name]'] = $account->getUsername();
 
     foreach ($tests as $input => $expected) {
only in patch2:
unchanged:
--- a/core/modules/system/lib/Drupal/system/Tests/Entity/FieldSqlStorageTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Entity/FieldSqlStorageTest.php
@@ -117,13 +117,13 @@ function testFieldLoad() {
       for ($delta = 0; $delta <= $this->field_cardinality; $delta++) {
         $value = mt_rand(1, 127);
         $values[$revision_id][] = $value;
-        $query->values(array($bundle, 0, $entity->id(), $revision_id, $delta, $entity->language()->id, $value));
+        $query->values(array($bundle, 0, $entity->id(), $revision_id, $delta, $entity->language()->getId(), $value));
       }
       $query->execute();
     }
     $query = db_insert($this->table)->fields($columns);
     foreach ($values[$revision_id] as $delta => $value) {
-      $query->values(array($bundle, 0, $entity->id(), $revision_id, $delta, $entity->language()->id, $value));
+      $query->values(array($bundle, 0, $entity->id(), $revision_id, $delta, $entity->language()->getId(), $value));
     }
     $query->execute();
 
@@ -187,7 +187,7 @@ function testFieldWrite() {
         'deleted' => 0,
         'entity_id' => $entity->id(),
         'revision_id' => $entity->getRevisionId(),
-        'langcode' => $entity->language()->id,
+        'langcode' => $entity->language()->getId(),
         'delta' => $delta,
         $this->field_name . '_value' => $values[$delta]['value'],
       );
@@ -210,7 +210,7 @@ function testFieldWrite() {
         'deleted' => 0,
         'entity_id' => $entity->id(),
         'revision_id' => $entity->getRevisionId(),
-        'langcode' => $entity->language()->id,
+        'langcode' => $entity->language()->getId(),
         'delta' => $delta,
         $this->field_name . '_value' => $values[$delta]['value'],
       );
@@ -238,7 +238,7 @@ function testFieldWrite() {
           'deleted' => 0,
           'entity_id' => $entity->id(),
           'revision_id' => $revision_id,
-          'langcode' => $entity->language()->id,
+          'langcode' => $entity->language()->getId(),
           'delta' => $delta,
           $this->field_name . '_value' => $values[$delta]['value'],
         );
only in patch2:
unchanged:
--- a/core/modules/system/tests/modules/entity_test/entity_test.module
+++ b/core/modules/system/tests/modules/entity_test/entity_test.module
@@ -392,28 +392,28 @@ function entity_test_entity_operation_alter(array &$operations, EntityInterface
  * Implements hook_entity_translation_insert().
  */
 function entity_test_entity_translation_insert(EntityInterface $translation) {
-  _entity_test_record_hooks('entity_translation_insert', $translation->language()->id);
+  _entity_test_record_hooks('entity_translation_insert', $translation->language()->getId());
 }
 
 /**
  * Implements hook_entity_translation_delete().
  */
 function entity_test_entity_translation_delete(EntityInterface $translation) {
-  _entity_test_record_hooks('entity_translation_delete', $translation->language()->id);
+  _entity_test_record_hooks('entity_translation_delete', $translation->language()->getId());
 }
 
 /**
  * Implements hook_ENTITY_TYPE_translation_insert().
  */
 function entity_test_entity_test_mul_translation_insert(EntityInterface $translation) {
-  _entity_test_record_hooks('entity_test_mul_translation_insert', $translation->language()->id);
+  _entity_test_record_hooks('entity_test_mul_translation_insert', $translation->language()->getId());
 }
 
 /**
  * Implements hook_ENTITY_TYPE_translation_delete().
  */
 function entity_test_entity_test_mul_translation_delete(EntityInterface $translation) {
-  _entity_test_record_hooks('entity_test_mul_translation_delete', $translation->language()->id);
+  _entity_test_record_hooks('entity_test_mul_translation_delete', $translation->language()->getId());
 }
 
 /**
only in patch2:
unchanged:
--- a/core/modules/taxonomy/lib/Drupal/taxonomy/Tests/TermLanguageTest.php
+++ b/core/modules/taxonomy/lib/Drupal/taxonomy/Tests/TermLanguageTest.php
@@ -63,7 +63,7 @@ function testTermLanguage() {
     $this->drupalPostForm(NULL, $edit, t('Save'));
     $terms = taxonomy_term_load_multiple_by_name($edit['name[0][value]']);
     $term = reset($terms);
-    $this->assertEqual($term->language()->id, $edit['langcode'], 'The term contains the correct langcode.');
+    $this->assertEqual($term->language()->getId(), $edit['langcode'], 'The term contains the correct langcode.');
 
     // Check if on the edit page the language is correct.
     $this->drupalGet('taxonomy/term/' . $term->id() . '/edit');
only in patch2:
unchanged:
--- a/core/modules/user/lib/Drupal/user/Tests/UserLanguageCreationTest.php
+++ b/core/modules/user/lib/Drupal/user/Tests/UserLanguageCreationTest.php
@@ -69,7 +69,7 @@ function testLocalUserCreation() {
 
     $user = user_load_by_name($username);
     $this->assertEqual($user->getPreferredLangcode(), $langcode, 'New user has correct preferred language set.');
-    $this->assertEqual($user->language()->id, $langcode, 'New user has correct profile language set.');
+    $this->assertEqual($user->language()->getId(), $langcode, 'New user has correct profile language set.');
 
     // Register a new user and check if the language selector is hidden.
     $this->drupalLogout();
@@ -87,7 +87,7 @@ function testLocalUserCreation() {
 
     $user = user_load_by_name($username);
     $this->assertEqual($user->getPreferredLangcode(), $langcode, 'New user has correct preferred language set.');
-    $this->assertEqual($user->language()->id, $langcode, 'New user has correct profile language set.');
+    $this->assertEqual($user->language()->getId(), $langcode, 'New user has correct profile language set.');
 
     // Test if the admin can use the language selector and if the
     // correct language is was saved.
only in patch2:
unchanged:
--- a/core/modules/views/lib/Drupal/views/Entity/Render/DefaultLanguageRenderer.php
+++ b/core/modules/views/lib/Drupal/views/Entity/Render/DefaultLanguageRenderer.php
@@ -24,7 +24,7 @@ class DefaultLanguageRenderer extends RendererBase {
    *   A language code.
    */
   protected function getLangcode(ResultRow $row) {
-    return $row->_entity->getUntranslated()->language()->id;
+    return $row->_entity->getUntranslated()->language()->getId();
   }
 
 }