diff --git a/core/config/schema/core.data_types.schema.yml b/core/config/schema/core.data_types.schema.yml
index faab889..f482e92 100644
--- a/core/config/schema/core.data_types.schema.yml
+++ b/core/config/schema/core.data_types.schema.yml
@@ -81,6 +81,14 @@ color_hex:
 
 # Complex extended data types:
 
+# Root of a configuration object.
+config_object:
+  type: mapping
+  mapping:
+    langcode:
+      type: string
+      label: 'Language code'
+
 # Mail text with subject and body parts.
 mail:
   type: mapping
@@ -121,7 +129,7 @@ action_configuration_default:
     type: string
 
 theme_settings:
-  type: mapping
+  type: config_object
   mapping:
     favicon:
       type: mapping
@@ -255,14 +263,14 @@ config_dependencies:
       label: 'Enforced configuration dependencies'
 
 config_entity:
-  type: mapping
+  type: config_object
   mapping:
     uuid:
       type: string
       label: 'UUID'
     langcode:
       type: string
-      label: 'Default language'
+      label: 'Language code'
     status:
       type: boolean
       label: 'Status'
@@ -416,9 +424,6 @@ core.date_format.*:
     pattern:
       type: date_format
       label: 'PHP date format'
-    langcode:
-      type: string
-      label: 'Default language'
 
 # Generic field settings schemas.
 
diff --git a/core/config/schema/core.extension.schema.yml b/core/config/schema/core.extension.schema.yml
index f53e5e6..bdc84b9 100644
--- a/core/config/schema/core.extension.schema.yml
+++ b/core/config/schema/core.extension.schema.yml
@@ -1,5 +1,5 @@
 core.extension:
-  type: mapping
+  type: config_object
   label: 'Extension settings'
   mapping:
     module:
diff --git a/core/config/schema/core.menu.schema.yml b/core/config/schema/core.menu.schema.yml
index 069ec19..1a6c268 100644
--- a/core/config/schema/core.menu.schema.yml
+++ b/core/config/schema/core.menu.schema.yml
@@ -1,5 +1,5 @@
 core.menu.static_menu_link_overrides:
-  type: mapping
+  type: config_object
   label: 'Static menu link overrides'
   mapping:
     definitions:
diff --git a/core/lib/Drupal/Core/Config/Schema/SchemaCheckTrait.php b/core/lib/Drupal/Core/Config/Schema/SchemaCheckTrait.php
index 00bbba5..5127adc 100644
--- a/core/lib/Drupal/Core/Config/Schema/SchemaCheckTrait.php
+++ b/core/lib/Drupal/Core/Config/Schema/SchemaCheckTrait.php
@@ -53,7 +53,7 @@ public function checkConfigSchema(TypedConfigManagerInterface $typed_config, $co
     if (!$typed_config->hasConfigSchema($config_name)) {
       return FALSE;
     }
-    $definition = $typed_config->getDefinition($config_name, TRUE, TRUE);
+    $definition = $typed_config->getDefinition($config_name);
     $data_definition = $typed_config->buildDataDefinition($definition, $config_data);
     $this->schema = $typed_config->create($data_definition, $config_data);
     $errors = array();
diff --git a/core/lib/Drupal/Core/Config/StorableConfigBase.php b/core/lib/Drupal/Core/Config/StorableConfigBase.php
index d4b1fb1..4af470e 100644
--- a/core/lib/Drupal/Core/Config/StorableConfigBase.php
+++ b/core/lib/Drupal/Core/Config/StorableConfigBase.php
@@ -128,7 +128,7 @@ public function getStorage() {
    */
   protected function getSchemaWrapper() {
     if (!isset($this->schemaWrapper)) {
-      $definition = $this->typedConfigManager->getDefinition($this->name, TRUE, TRUE);
+      $definition = $this->typedConfigManager->getDefinition($this->name);
       $data_definition = $this->typedConfigManager->buildDataDefinition($definition, $this->data);
       $this->schemaWrapper = $this->typedConfigManager->create($data_definition, $this->data);
     }
diff --git a/core/lib/Drupal/Core/Config/TypedConfigManager.php b/core/lib/Drupal/Core/Config/TypedConfigManager.php
index a086e34..244747a 100644
--- a/core/lib/Drupal/Core/Config/TypedConfigManager.php
+++ b/core/lib/Drupal/Core/Config/TypedConfigManager.php
@@ -72,7 +72,7 @@ public function __construct(StorageInterface $configStorage, StorageInterface $s
    */
   public function get($name) {
     $data = $this->configStorage->read($name);
-    $type_definition = $this->getDefinition($name, TRUE, TRUE);
+    $type_definition = $this->getDefinition($name);
     $data_definition = $this->buildDataDefinition($type_definition, $data);
     return $this->create($data_definition, $data);
   }
diff --git a/core/lib/Drupal/Core/Config/TypedConfigManagerInterface.php b/core/lib/Drupal/Core/Config/TypedConfigManagerInterface.php
index 402cb82..e9e562e 100644
--- a/core/lib/Drupal/Core/Config/TypedConfigManagerInterface.php
+++ b/core/lib/Drupal/Core/Config/TypedConfigManagerInterface.php
@@ -111,8 +111,8 @@ public function hasConfigSchema($name);
    *   Ignored with TypedConfigManagerInterface. Kept for compatibility with
    *   DiscoveryInterface.
    * @param bool $is_config_name
-   *   Set to TRUE if $plugin_id is a configuration name (as opposed to an
-   *   internal configuration schema type).
+   *   (deprecated) Set to TRUE if $plugin_id is a configuration name (as
+   *   opposed to an internal configuration schema type).
    *
    * @return array
    *   A plugin definition array. If the given plugin id does not have typed
diff --git a/core/modules/config/src/Tests/ConfigSchemaTest.php b/core/modules/config/src/Tests/ConfigSchemaTest.php
index cf945d9..cf7cc08 100644
--- a/core/modules/config/src/Tests/ConfigSchemaTest.php
+++ b/core/modules/config/src/Tests/ConfigSchemaTest.php
@@ -101,7 +101,7 @@ function testSchemaMapping() {
       'type' => 'text',
     );
     $expected['mapping']['langcode'] = array(
-      'label' => 'Default language',
+      'label' => 'Language code',
       'type' => 'string',
     );
     $expected['type'] = 'system.maintenance';
@@ -156,7 +156,7 @@ function testSchemaMapping() {
     $expected['mapping']['uuid']['type'] = 'string';
     $expected['mapping']['uuid']['label'] = 'UUID';
     $expected['mapping']['langcode']['type'] = 'string';
-    $expected['mapping']['langcode']['label'] = 'Default language';
+    $expected['mapping']['langcode']['label'] = 'Language code';
     $expected['mapping']['status']['type'] = 'boolean';
     $expected['mapping']['status']['label'] = 'Status';
     $expected['mapping']['dependencies']['type'] = 'config_dependencies';
diff --git a/core/modules/config_translation/tests/modules/config_translation_test/config/schema/config_translation_test.schema.yml b/core/modules/config_translation/tests/modules/config_translation_test/config/schema/config_translation_test.schema.yml
index a5ff2e6..63b8475 100644
--- a/core/modules/config_translation/tests/modules/config_translation_test/config/schema/config_translation_test.schema.yml
+++ b/core/modules/config_translation/tests/modules/config_translation_test/config/schema/config_translation_test.schema.yml
@@ -1,7 +1,7 @@
 # Schema for the configuration files of the Configuration translation test module.
 
 config_translation_test.content:
-  type: mapping
+  type: config_object
   label: 'Content'
   mapping:
     id:
@@ -10,9 +10,6 @@ config_translation_test.content:
     label:
       type: label
       label: 'Label'
-    langcode:
-      type: string
-      label: 'Default language'
     content:
       type: text_format
       label: 'Content'
diff --git a/core/modules/field/config/schema/field.schema.yml b/core/modules/field/config/schema/field.schema.yml
index 9ea9b2e..55760a7 100644
--- a/core/modules/field/config/schema/field.schema.yml
+++ b/core/modules/field/config/schema/field.schema.yml
@@ -1,7 +1,7 @@
 # Schema for configuration files of the Field module.
 
 field.settings:
-  type: mapping
+  type: config_object
   label: 'Field settings'
   mapping:
     purge_batch_size:
diff --git a/core/modules/filter/config/schema/filter.schema.yml b/core/modules/filter/config/schema/filter.schema.yml
index ac956f7..ab035e1 100644
--- a/core/modules/filter/config/schema/filter.schema.yml
+++ b/core/modules/filter/config/schema/filter.schema.yml
@@ -35,9 +35,6 @@ filter.format.*:
       label: 'Enabled filters'
       sequence:
         type: filter
-    langcode:
-      type: string
-      label: 'Default language'
     dependencies:
       type: config_dependencies
       label: 'Dependencies'
diff --git a/core/modules/language/config/install/language.mappings.yml b/core/modules/language/config/install/language.mappings.yml
index f7fc321..5c64193 100644
--- a/core/modules/language/config/install/language.mappings.yml
+++ b/core/modules/language/config/install/language.mappings.yml
@@ -1,12 +1,13 @@
 # Browsers use different language codes to refer to the same languages,
 # these defaults handles the most common cases.
-no: 'nb' # Norwegian
-pt: 'pt-pt' # Portuguese
-zh: 'zh-hans' # Default Chinese to simplified script
-zh-tw: 'zh-hant' # Taiwan Chinese in traditional script
-zh-hk: 'zh-hant' # Hong Kong Chinese in traditional script
-zh-mo: 'zh-hant' # Macao Chinese in traditional script
-zh-cht: 'zh-hant' # traditional Chinese
-zh-cn: 'zh-hans' # PRC Mainland Chinese in simplified script
-zh-sg: 'zh-hans' # Singapore Chinese in simplified script
-zh-chs: 'zh-hans' # simplified Chinese
+map:
+  no: 'nb' # Norwegian
+  pt: 'pt-pt' # Portuguese
+  zh: 'zh-hans' # Default Chinese to simplified script
+  zh-tw: 'zh-hant' # Taiwan Chinese in traditional script
+  zh-hk: 'zh-hant' # Hong Kong Chinese in traditional script
+  zh-mo: 'zh-hant' # Macao Chinese in traditional script
+  zh-cht: 'zh-hant' # traditional Chinese
+  zh-cn: 'zh-hans' # PRC Mainland Chinese in simplified script
+  zh-sg: 'zh-hans' # Singapore Chinese in simplified script
+  zh-chs: 'zh-hans' # simplified Chinese
diff --git a/core/modules/language/config/schema/language.schema.yml b/core/modules/language/config/schema/language.schema.yml
index 6c082e1..5e3f55b 100644
--- a/core/modules/language/config/schema/language.schema.yml
+++ b/core/modules/language/config/schema/language.schema.yml
@@ -18,7 +18,7 @@ language_type_negotiation:
         label: Weight
 
 language.types:
-  type: mapping
+  type: config_object
   label: 'Language types'
   mapping:
     all:
@@ -41,7 +41,7 @@ language.types:
         label: 'Language negotiation per type setting'
 
 language.negotiation:
-  type: mapping
+  type: config_object
   label: 'Language detection methods'
   mapping:
     session:
@@ -75,11 +75,14 @@ language.negotiation:
       label: 'Selected language'
 
 language.mappings:
-  type: sequence
+  type: config_object
   label: 'Language mapping'
-  sequence:
-    type: string
-    label: 'Language'
+  mapping:
+    map:
+      type: sequence
+      sequence:
+        type: string
+        label: 'Language'
 
 language.entity.*:
   type: config_entity
diff --git a/core/modules/language/language.module b/core/modules/language/language.module
index ae8c2e2..4e7f017 100644
--- a/core/modules/language/language.module
+++ b/core/modules/language/language.module
@@ -448,7 +448,7 @@ function language_get_browser_drupal_langcode_mappings() {
   if ($config->isNew()) {
     return array();
   }
-  return $config->get();
+  return $config->get('map');
 }
 
 /**
diff --git a/core/modules/language/src/Form/NegotiationBrowserDeleteForm.php b/core/modules/language/src/Form/NegotiationBrowserDeleteForm.php
index 1dc1447..73e0246 100644
--- a/core/modules/language/src/Form/NegotiationBrowserDeleteForm.php
+++ b/core/modules/language/src/Form/NegotiationBrowserDeleteForm.php
@@ -71,7 +71,7 @@ public function buildForm(array $form, FormStateInterface $form_state, $browser_
    */
   public function submitForm(array &$form, FormStateInterface $form_state) {
     $this->config('language.mappings')
-      ->clear($this->browserLangcode)
+      ->clear('map.' . $this->browserLangcode)
       ->save();
 
     $args = array(
diff --git a/core/modules/language/src/Form/NegotiationBrowserForm.php b/core/modules/language/src/Form/NegotiationBrowserForm.php
index 14ebb62..bf0ce4e 100644
--- a/core/modules/language/src/Form/NegotiationBrowserForm.php
+++ b/core/modules/language/src/Form/NegotiationBrowserForm.php
@@ -180,7 +180,7 @@ public function submitForm(array &$form, FormStateInterface $form_state) {
     $mappings = $form_state->get('mappings');
     if (!empty($mappings)) {
       $config = $this->config('language.mappings');
-      $config->setData($mappings);
+      $config->setData(['map' => $mappings]);
       $config->save();
     }
 
@@ -198,7 +198,7 @@ protected function language_get_browser_drupal_langcode_mappings() {
     if ($config->isNew()) {
       return array();
     }
-    return $config->get();
+    return $config->get('map');
   }
 }
 
diff --git a/core/modules/language/src/Plugin/LanguageNegotiation/LanguageNegotiationBrowser.php b/core/modules/language/src/Plugin/LanguageNegotiation/LanguageNegotiationBrowser.php
index e9fc38e..9acd295 100644
--- a/core/modules/language/src/Plugin/LanguageNegotiation/LanguageNegotiationBrowser.php
+++ b/core/modules/language/src/Plugin/LanguageNegotiation/LanguageNegotiationBrowser.php
@@ -39,7 +39,7 @@ public function getLangcode(Request $request = NULL) {
     if ($this->languageManager && $request && $request->server->get('HTTP_ACCEPT_LANGUAGE')) {
       $http_accept_language = $request->server->get('HTTP_ACCEPT_LANGUAGE');
       $langcodes = array_keys($this->languageManager->getLanguages());
-      $mappings = $this->config->get('language.mappings')->get();
+      $mappings = $this->config->get('language.mappings')->get('map');
       $langcode = UserAgent::getBestMatchingLangcode($http_accept_language, $langcodes, $mappings);
     }
 
diff --git a/core/modules/locale/src/LocaleConfigManager.php b/core/modules/locale/src/LocaleConfigManager.php
index 17d1e8f..d10cf18 100644
--- a/core/modules/locale/src/LocaleConfigManager.php
+++ b/core/modules/locale/src/LocaleConfigManager.php
@@ -134,7 +134,7 @@ public function getTranslatableDefaultConfig($name) {
     if ($this->isSupported($name)) {
       // Create typed configuration wrapper based on install storage data.
       $data = $this->installStorageRead($name);
-      $type_definition = $this->typedConfigManager->getDefinition($name, TRUE, TRUE);
+      $type_definition = $this->typedConfigManager->getDefinition($name);
       $data_definition = $this->typedConfigManager->buildDataDefinition($type_definition, $data);
       $typed_config = $this->typedConfigManager->create($data_definition, $data);
       if ($typed_config instanceof TraversableTypedDataInterface) {
diff --git a/core/modules/locale/tests/modules/locale_test/config/schema/locale_test.schema.yml b/core/modules/locale/tests/modules/locale_test/config/schema/locale_test.schema.yml
index daf3391..f6cf7b9 100644
--- a/core/modules/locale/tests/modules/locale_test/config/schema/locale_test.schema.yml
+++ b/core/modules/locale/tests/modules/locale_test/config/schema/locale_test.schema.yml
@@ -1,7 +1,7 @@
 # Schema for the configuration files of the Locale Test module.
 
 locale_test.no_translation:
-  type: mapping
+  type: config_object
   label: 'No traslation settings'
   mapping:
     test:
@@ -9,11 +9,9 @@ locale_test.no_translation:
       label: 'Test'
       # See \Drupal\locale\Tests\LocaleConfigSubscriberTest
       translatable: true
-    langcode:
-      type: string
 
 locale_test.translation:
-  type: mapping
+  type: config_object
   label: 'translation settings'
   mapping:
     test:
@@ -21,5 +19,3 @@ locale_test.translation:
       label: 'Test'
       # See \Drupal\locale\Tests\LocaleConfigSubscriberTest
       translatable: true
-    langcode:
-      type: string
diff --git a/core/modules/migrate_drupal/config/schema/migrate_drupal.source.schema.yml b/core/modules/migrate_drupal/config/schema/migrate_drupal.source.schema.yml
index e43ffe8..578a169 100644
--- a/core/modules/migrate_drupal/config/schema/migrate_drupal.source.schema.yml
+++ b/core/modules/migrate_drupal/config/schema/migrate_drupal.source.schema.yml
@@ -328,7 +328,7 @@ migrate_entity_constant:
       label: 'Parent'
     langcode:
       type: string
-      label: 'Type'
+      label: 'Language code'
     third_party_settings:
       type: sequence
       label: 'Settings'
diff --git a/core/modules/system/config/schema/system.schema.yml b/core/modules/system/config/schema/system.schema.yml
index ba8fa15..3ba947e 100644
--- a/core/modules/system/config/schema/system.schema.yml
+++ b/core/modules/system/config/schema/system.schema.yml
@@ -1,7 +1,7 @@
 # Schema for the configuration files of the System module.
 
 system.site:
-  type: mapping
+  type: config_object
   label: 'Site information'
   mapping:
     uuid:
@@ -35,9 +35,6 @@ system.site:
     weight_select_max:
       type: integer
       label: 'Weight element maximum value'
-    langcode:
-      type: string
-      label: 'Language code'
     default_langcode:
       type: string
       label: 'Site default language code'
@@ -46,18 +43,15 @@ system.site:
       label: 'Notification email address'
 
 system.maintenance:
-  type: mapping
+  type: config_object
   label: 'Maintenance mode'
   mapping:
     message:
       type: text
       label: 'Message to display when in maintenance mode'
-    langcode:
-      type: string
-      label: 'Default language'
 
 system.authorize:
-  type: mapping
+  type: config_object
   label: 'Authorize settings'
   mapping:
     filetransfer_default:
@@ -65,7 +59,7 @@ system.authorize:
       label: 'Default file transfer protocol'
 
 system.cron:
-  type: mapping
+  type: config_object
   label: 'Cron settings'
   mapping:
     threshold:
@@ -83,7 +77,7 @@ system.cron:
           label: 'Requirements error period'
 
 system.date:
-  type: mapping
+  type: config_object
   label: 'Date settings'
   mapping:
     first_day:
@@ -96,9 +90,6 @@ system.date:
         default:
           type: string
           label: 'Default country'
-    langcode:
-      type: string
-      label: 'Default language'
     timezone:
       type: mapping
       label: 'Time zone settings'
@@ -121,7 +112,7 @@ system.date:
               label: 'Remind users at login if their time zone is not set'
 
 system.diff:
-  type: mapping
+  type: config_object
   label: 'Diff settings'
   mapping:
     context:
@@ -136,7 +127,7 @@ system.diff:
           label: 'Number of trailing lines in a diff'
 
 system.filter:
-  type: mapping
+  type: config_object
   label: 'Filter settings'
   mapping:
     protocols:
@@ -147,7 +138,7 @@ system.filter:
         label: 'Protocol'
 
 system.logging:
-  type: mapping
+  type: config_object
   label: 'Logging settings'
   mapping:
     error_level:
@@ -155,7 +146,7 @@ system.logging:
       label: 'Error messages to display'
 
 system.performance:
-  type: mapping
+  type: config_object
   label: 'Performance settings'
   mapping:
     cache:
@@ -220,7 +211,7 @@ system.performance:
       label: 'Stale file threshold'
 
 system.rss:
-  type: mapping
+  type: config_object
   label: 'Feed settings'
   mapping:
     channel:
@@ -240,12 +231,9 @@ system.rss:
         view_mode:
           type: string
           label: 'Feed content'
-    langcode:
-      type: string
-      label: 'Default language'
 
 system.theme:
-  type: mapping
+  type: config_object
   label: 'Theme settings'
   mapping:
     admin:
@@ -292,7 +280,7 @@ system.action.*:
       type: action.configuration.[%parent.plugin]
 
 system.file:
-  type: mapping
+  type: config_object
   label: 'File system'
   mapping:
     allow_insecure_uploads:
@@ -313,7 +301,7 @@ system.file:
       label: 'Maximum age for temporary files'
 
 system.image:
-  type: mapping
+  type: config_object
   label: 'Image settings'
   mapping:
     toolkit:
@@ -321,7 +309,7 @@ system.image:
       label: 'Toolkit'
 
 system.image.gd:
-  type: mapping
+  type: config_object
   label: 'Image settings'
   mapping:
     jpeg_quality:
@@ -329,7 +317,7 @@ system.image.gd:
       label: 'JPEG quality'
 
 system.mail:
-  type: mapping
+  type: config_object
   label: 'Mail system'
   mapping:
     interface:
diff --git a/core/modules/user/config/schema/user.schema.yml b/core/modules/user/config/schema/user.schema.yml
index 09e5989..9d853c1 100644
--- a/core/modules/user/config/schema/user.schema.yml
+++ b/core/modules/user/config/schema/user.schema.yml
@@ -1,7 +1,7 @@
 # Schema for the configuration files of the User module.
 
 user.settings:
-  type: mapping
+  type: config_object
   label: 'User settings'
   mapping:
     anonymous:
@@ -50,12 +50,9 @@ user.settings:
     password_strength:
       type: boolean
       label: 'Enable password strength indicator'
-    langcode:
-      type: string
-      label: 'Default language'
 
 user.mail:
- type: mapping
+ type: config_object
  label: 'Email settings'
  mapping:
   cancel_confirm:
@@ -85,12 +82,9 @@ user.mail:
   status_canceled:
     type: mail
     label: 'Account cancelled'
-  langcode:
-    type: string
-    label: 'Default language'
 
 user.flood:
-  type: mapping
+  type: config_object
   label: 'User flood settings'
   mapping:
     uid_only: