diff --git a/core/lib/Drupal/Core/Entity/ContentEntityDatabaseStorage.php b/core/lib/Drupal/Core/Entity/ContentEntityDatabaseStorage.php
index 6b7de03..d607cec 100644
--- a/core/lib/Drupal/Core/Entity/ContentEntityDatabaseStorage.php
+++ b/core/lib/Drupal/Core/Entity/ContentEntityDatabaseStorage.php
@@ -1192,7 +1192,7 @@ public static function _fieldSqlSchema(FieldConfigInterface $field, array $schem
 
     // Define the entity ID schema based on the field definitions.
     $id_definition = $definitions[$entity_type->getKey('id')];
-    if ($id_definition->getType() == 'integer') {
+    if ($id_definition->getTypeId() == 'integer') {
       $id_schema = array(
         'type' => 'int',
         'unsigned' => TRUE,
@@ -1212,7 +1212,7 @@ public static function _fieldSqlSchema(FieldConfigInterface $field, array $schem
     // Define the revision ID schema, default to integer if there is no revision
     // ID.
     $revision_id_definition = $entity_type->hasKey('revision_id') ? $definitions[$entity_type->getKey('revision_id')] : NULL;
-    if (!$revision_id_definition || $revision_id_definition->getType() == 'integer') {
+    if (!$revision_id_definition || $revision_id_definition->getTypeId() == 'integer') {
       $revision_id_schema = array(
         'type' => 'int',
         'unsigned' => TRUE,
diff --git a/core/lib/Drupal/Core/Entity/EntityManager.php b/core/lib/Drupal/Core/Entity/EntityManager.php
index 930b7ec..9a30d41 100644
--- a/core/lib/Drupal/Core/Entity/EntityManager.php
+++ b/core/lib/Drupal/Core/Entity/EntityManager.php
@@ -101,6 +101,9 @@ class EntityManager extends PluginManagerBase implements EntityManagerInterface
   /**
    * Static cache of storage field definitions per entity type.
    *
+   * Elements of the array:
+   *  - $entity_type_id: \Drupal\Core\Field\FieldDefinition[]
+   *
    * @var array
    */
   protected $storageFieldDefinitions;
@@ -355,8 +358,8 @@ protected function buildBaseFieldDefinitions($entity_type_id) {
     $base_field_definitions = $class::baseFieldDefinitions($entity_type);
     $provider = $entity_type->getProvider();
     foreach ($base_field_definitions as $definition) {
-      // @todo Remove this check one FieldDefinitionInterface exposes a proper
-      //   provider setter. See https://drupal.org/node/2225961.
+      // @todo Remove this check once FieldDefinitionInterface exposes a proper
+      //  provider setter. See https://drupal.org/node/2225961.
       if ($definition instanceof FieldDefinition) {
         $definition->setProvider($provider);
       }
@@ -369,8 +372,8 @@ protected function buildBaseFieldDefinitions($entity_type_id) {
         // Ensure the provider key actually matches the name of the provider
         // defining the field.
         foreach ($module_definitions as $field_name => $definition) {
-          // @todo Remove this check one FieldDefinitionInterface exposes a
-          //   proper provider setter. See https://drupal.org/node/2225961.
+          // @todo Remove this check once FieldDefinitionInterface exposes a
+          //  proper provider setter. See https://drupal.org/node/2225961.
           if ($definition instanceof FieldDefinition) {
             $definition->setProvider($module);
           }
@@ -452,8 +455,8 @@ protected function buildBundleFieldDefinitions($entity_type_id, $bundle, array $
     $bundle_field_definitions = $class::bundleFieldDefinitions($entity_type, $bundle, $base_field_definitions);
     $provider = $entity_type->getProvider();
     foreach ($bundle_field_definitions as $definition) {
-      // @todo Remove this check one FieldDefinitionInterface exposes a proper
-      //   provider setter. See https://drupal.org/node/2225961.
+      // @todo Remove this check once FieldDefinitionInterface exposes a proper
+      //  provider setter. See https://drupal.org/node/2225961.
       if ($definition instanceof FieldDefinition) {
         $definition->setProvider($provider);
       }
@@ -466,8 +469,8 @@ protected function buildBundleFieldDefinitions($entity_type_id, $bundle, array $
         // Ensure the provider key actually matches the name of the provider
         // defining the field.
         foreach ($module_definitions as $field_name => $definition) {
-          // @todo Remove this check one FieldDefinitionInterface exposes a
-          //   proper provider setter. See https://drupal.org/node/2225961.
+          // @todo Remove this check once FieldDefinitionInterface exposes a
+          //  proper provider setter. See https://drupal.org/node/2225961.
           if ($definition instanceof FieldDefinition) {
             $definition->setProvider($module);
           }
@@ -532,8 +535,8 @@ protected function buildStorageFieldDefinitions($entity_type_id) {
         // Ensure the provider key actually matches the name of the provider
         // defining the field.
         foreach ($module_definitions as $field_name => $definition) {
-          // @todo Remove this check one FieldDefinitionInterface exposes a
-          //   proper provider setter. See https://drupal.org/node/2225961.
+          // @todo Remove this check once FieldDefinitionInterface exposes a
+          //  proper provider setter. See https://drupal.org/node/2225961.
           if ($definition instanceof FieldDefinition) {
             $definition->setProvider($module);
           }
diff --git a/core/lib/Drupal/Core/Field/FieldDefinition.php b/core/lib/Drupal/Core/Field/FieldDefinition.php
index 732c93f..ffce944 100644
--- a/core/lib/Drupal/Core/Field/FieldDefinition.php
+++ b/core/lib/Drupal/Core/Field/FieldDefinition.php
@@ -82,7 +82,7 @@ public static function create($type) {
    * @return $this
    */
   public static function createFromFieldStorageDefinition(StorageFieldDefinitionInterface $definition) {
-    return static::create($definition->getType())
+    return static::create($definition->getTypeId())
       ->setCardinality($definition->getCardinality())
       ->setConstraints($definition->getConstraints())
       ->setCustomStorage($definition->hasCustomStorage())
@@ -131,7 +131,7 @@ public function setName($name) {
   /**
    * {@inheritdoc}
    */
-  public function getType() {
+  public function getTypeId() {
     return $this->type;
   }
 
@@ -474,7 +474,7 @@ public function setTargetEntityTypeId($entity_type_id) {
   public function getSchema() {
     if (!isset($this->schema)) {
       // Get the schema from the field item class.
-      $definition = \Drupal::service('plugin.manager.field.field_type')->getDefinition($this->getType());
+      $definition = \Drupal::service('plugin.manager.field.field_type')->getDefinition($this->getTypeId());
       $class = $definition['class'];
       $schema = $class::schema($this);
       // Fill in default values for optional entries.
diff --git a/core/lib/Drupal/Core/Field/FormatterBase.php b/core/lib/Drupal/Core/Field/FormatterBase.php
index 1b4287f..29fa270 100644
--- a/core/lib/Drupal/Core/Field/FormatterBase.php
+++ b/core/lib/Drupal/Core/Field/FormatterBase.php
@@ -84,7 +84,7 @@ public function view(FieldItemListInterface $items) {
         '#view_mode' => $this->viewMode,
         '#language' => $items->getLangcode(),
         '#field_name' => $field_name,
-        '#field_type' => $this->fieldDefinition->getType(),
+        '#field_type' => $this->fieldDefinition->getTypeId(),
         '#field_translatable' => $this->fieldDefinition->isTranslatable(),
         '#entity_type' => $entity_type,
         '#bundle' => $entity->bundle(),
diff --git a/core/lib/Drupal/Core/Field/Plugin/Field/FieldWidget/NumberWidget.php b/core/lib/Drupal/Core/Field/Plugin/Field/FieldWidget/NumberWidget.php
index fa31ce7..62d8fe8 100644
--- a/core/lib/Drupal/Core/Field/Plugin/Field/FieldWidget/NumberWidget.php
+++ b/core/lib/Drupal/Core/Field/Plugin/Field/FieldWidget/NumberWidget.php
@@ -79,7 +79,7 @@ public function formElement(FieldItemListInterface $items, $delta, array $elemen
     );
 
     // Set the step for floating point and decimal numbers.
-    switch ($this->fieldDefinition->getType()) {
+    switch ($this->fieldDefinition->getTypeId()) {
       case 'decimal':
         $element['#step'] = pow(0.1, $field_settings['scale']);
         break;
diff --git a/core/lib/Drupal/Core/Field/StorageFieldDefinitionInterface.php b/core/lib/Drupal/Core/Field/StorageFieldDefinitionInterface.php
index 735d4b8..a330635 100644
--- a/core/lib/Drupal/Core/Field/StorageFieldDefinitionInterface.php
+++ b/core/lib/Drupal/Core/Field/StorageFieldDefinitionInterface.php
@@ -44,7 +44,7 @@ public function getName();
    *
    * @see \Drupal\Core\Field\FieldTypePluginManagerInterface
    */
-  public function getType();
+  public function getTypeId();
 
   /**
    * Returns the field settings.
@@ -53,7 +53,7 @@ public function getType();
    * For example, a text field can define a 'max_length' setting, and an image
    * field can define a 'alt_field_required' setting.
    *
-   * @return array
+   * @return mixed[]
    *   An array of key/value pairs.
    */
   public function getSettings();
@@ -119,7 +119,7 @@ public function getDescription();
    * Possible values are positive integers or
    * FieldDefinitionInterface::CARDINALITY_UNLIMITED.
    *
-   * @return integer
+   * @return int
    *   The field cardinality.
    */
   public function getCardinality();
@@ -174,7 +174,7 @@ public function getPropertyDefinitions();
    * while a link field might contain 'title' and 'url' properties, and a text
    * field might contain 'value', 'summary', and 'format' properties.
    *
-   * @return array
+   * @return string[]
    *   The property names.
    */
   public function getPropertyNames();
@@ -213,7 +213,7 @@ public function getTargetEntityTypeId();
    * Note that this method returns an empty array for computed fields which have
    * no schema.
    *
-   * @return array
+   * @return array[]
    *   The field schema, as an array of key/value pairs in the format returned
    *   by hook_field_schema():
    *   - columns: An array of Schema API column specifications, keyed by column
@@ -231,7 +231,7 @@ public function getSchema();
   /**
    * Returns the field columns, as defined in the field schema.
    *
-   * @return array
+   * @return array[]
    *   The array of field columns, keyed by column name, in the same format
    *   returned by getSchema().
    *
@@ -244,10 +244,12 @@ public function getColumns();
    *
    * See \Drupal\Core\TypedData\TypedDataManager::getConstraints() for details.
    *
-   * @return array
+   * @return array[]
    *   An array of validation constraint definitions, keyed by constraint name.
    *   Each constraint definition can be used for instantiating
    *   \Symfony\Component\Validator\Constraint objects.
+   *
+   * @see \Symfony\Component\Validator\Constraint
    */
   public function getConstraints();
 
@@ -262,6 +264,8 @@ public function getConstraints();
    * @return array
    *   A validation constraint definition which can be used for instantiating a
    *   \Symfony\Component\Validator\Constraint object.
+   *
+   * @see \Symfony\Component\Validator\Constraint
    */
   public function getConstraint($constraint_name);
 
diff --git a/core/lib/Drupal/Core/Field/TypedData/FieldItemDataDefinition.php b/core/lib/Drupal/Core/Field/TypedData/FieldItemDataDefinition.php
index dbf81c6..6ed9ba7 100644
--- a/core/lib/Drupal/Core/Field/TypedData/FieldItemDataDefinition.php
+++ b/core/lib/Drupal/Core/Field/TypedData/FieldItemDataDefinition.php
@@ -51,7 +51,7 @@ public static function createFromDataType($data_type) {
    * @return static
    */
   public static function create($field_definition) {
-    $definition['type'] = 'field_item:' . $field_definition->getType();
+    $definition['type'] = 'field_item:' . $field_definition->getTypeId();
     $item_definition = new static($definition);
     $item_definition->fieldDefinition = $field_definition;
     return $item_definition;
diff --git a/core/lib/Drupal/Core/Field/WidgetBase.php b/core/lib/Drupal/Core/Field/WidgetBase.php
index 33ea5d8..c8dfde1 100644
--- a/core/lib/Drupal/Core/Field/WidgetBase.php
+++ b/core/lib/Drupal/Core/Field/WidgetBase.php
@@ -118,7 +118,7 @@ public function form(FieldItemListInterface $items, array &$form, array &$form_s
       '#parents' => array_merge($parents, array($field_name . '_wrapper')),
       '#attributes' => array(
         'class' => array(
-          'field-type-' . drupal_html_class($this->fieldDefinition->getType()),
+          'field-type-' . drupal_html_class($this->fieldDefinition->getTypeId()),
           'field-name-' . drupal_html_class($field_name),
           'field-widget-' . drupal_html_class($this->getPluginId()),
         ),
diff --git a/core/modules/comment/comment.module b/core/modules/comment/comment.module
index 9ee58fc..47d4409 100644
--- a/core/modules/comment/comment.module
+++ b/core/modules/comment/comment.module
@@ -193,7 +193,7 @@ function comment_count_unpublished() {
  * Implements hook_ENTITY_TYPE_insert() for 'field_instance_config'.
  */
 function comment_field_instance_config_insert(FieldInstanceConfigInterface $instance) {
-  if ($instance->getType() == 'comment' && !$instance->isSyncing()) {
+  if ($instance->getTypeId() == 'comment' && !$instance->isSyncing()) {
     \Drupal::service('comment.manager')->addBodyField($instance->entity_type, $instance->getName());
   }
 }
@@ -202,7 +202,7 @@ function comment_field_instance_config_insert(FieldInstanceConfigInterface $inst
  * Implements hook_ENTITY_TYPE_create() for 'field_instance_config'.
  */
 function comment_field_instance_config_create(FieldInstanceConfigInterface $instance) {
-  if ($instance->getType() == 'comment' && !$instance->isSyncing()) {
+  if ($instance->getTypeId() == 'comment' && !$instance->isSyncing()) {
     // Assign default values for the field instance.
     if (!isset($instance->default_value)) {
       $instance->default_value = array();
@@ -223,7 +223,7 @@ function comment_field_instance_config_create(FieldInstanceConfigInterface $inst
  * Implements hook_ENTITY_TYPE_update() for 'field_instance_config'.
  */
 function comment_field_instance_config_update(FieldInstanceConfigInterface $instance) {
-  if ($instance->getType() == 'comment') {
+  if ($instance->getTypeId() == 'comment') {
     // Comment field settings also affects the rendering of *comment* entities,
     // not only the *commented* entities.
     \Drupal::entityManager()->getViewBuilder('comment')->resetCache();
@@ -234,7 +234,7 @@ function comment_field_instance_config_update(FieldInstanceConfigInterface $inst
  * Implements hook_ENTITY_TYPE_delete() for 'field_config'.
  */
 function comment_field_config_delete(FieldConfigInterface $field) {
-  if ($field->getType() == 'comment') {
+  if ($field->getTypeId() == 'comment') {
     // Delete all fields and displays attached to the comment bundle.
     entity_invoke_bundle_hook('delete', 'comment', $field->entity_type . '__' . $field->getName());
   }
@@ -244,7 +244,7 @@ function comment_field_config_delete(FieldConfigInterface $field) {
  * Implements hook_ENTITY_TYPE_delete() for 'field_instance_config'.
  */
 function comment_field_instance_config_delete(FieldInstanceConfigInterface $instance) {
-  if ($instance->getType() == 'comment') {
+  if ($instance->getTypeId() == 'comment') {
     // Delete all comments that used by the entity bundle.
     $comments = db_query("SELECT cid FROM {comment} WHERE entity_type = :entity_type AND field_id = :field_id", array(
       ':entity_type' => $instance->getEntityTypeId(),
diff --git a/core/modules/content_translation/content_translation.admin.inc b/core/modules/content_translation/content_translation.admin.inc
index 96b8d3c..7122d9c 100644
--- a/core/modules/content_translation/content_translation.admin.inc
+++ b/core/modules/content_translation/content_translation.admin.inc
@@ -23,7 +23,7 @@
 function content_translation_field_sync_widget(FieldDefinitionInterface $field) {
   $element = array();
 
-  $definition = \Drupal::service('plugin.manager.field.field_type')->getDefinition($field->getType());
+  $definition = \Drupal::service('plugin.manager.field.field_type')->getDefinition($field->getTypeId());
   $column_groups = $definition['column_groups'];
   if (!empty($column_groups) && count($column_groups) > 1) {
     $options = array();
diff --git a/core/modules/edit/lib/Drupal/edit/Form/EditFieldForm.php b/core/modules/edit/lib/Drupal/edit/Form/EditFieldForm.php
index 13bf441..99eedad 100644
--- a/core/modules/edit/lib/Drupal/edit/Form/EditFieldForm.php
+++ b/core/modules/edit/lib/Drupal/edit/Form/EditFieldForm.php
@@ -242,7 +242,7 @@ protected function simplify(array &$form, array &$form_state) {
    */
   protected function getChangedFieldName(ContentEntityInterface $entity) {
     foreach ($entity->getFieldDefinitions() as $field) {
-      if ($field->getType() == 'changed') {
+      if ($field->getTypeId() == 'changed') {
         return $field->getName();
       }
     }
diff --git a/core/modules/entity/lib/Drupal/entity/EntityDisplayBase.php b/core/modules/entity/lib/Drupal/entity/EntityDisplayBase.php
index dd1bfa0..b79985f 100644
--- a/core/modules/entity/lib/Drupal/entity/EntityDisplayBase.php
+++ b/core/modules/entity/lib/Drupal/entity/EntityDisplayBase.php
@@ -261,7 +261,7 @@ protected function init() {
           $this->hidden[$name] = TRUE;
         }
         elseif ($options) {
-          $this->content[$name] = $this->pluginManager->prepareConfiguration($definition->getType(), $options);
+          $this->content[$name] = $this->pluginManager->prepareConfiguration($definition->getTypeId(), $options);
         }
         // Note: (base) fields that do not specify display options are not
         // tracked in the display at all, in order to avoid cluttering the
@@ -305,7 +305,7 @@ public function setComponent($name, array $options = array()) {
 
     // For a field, fill in default options.
     if ($field_definition = $this->getFieldDefinition($name)) {
-      $options = $this->pluginManager->prepareConfiguration($field_definition->getType(), $options);
+      $options = $this->pluginManager->prepareConfiguration($field_definition->getTypeId(), $options);
     }
 
     $this->content[$name] = $options;
diff --git a/core/modules/entity_reference/lib/Drupal/entity_reference/EntityReferenceController.php b/core/modules/entity_reference/lib/Drupal/entity_reference/EntityReferenceController.php
index 2383ba6..f86393e 100644
--- a/core/modules/entity_reference/lib/Drupal/entity_reference/EntityReferenceController.php
+++ b/core/modules/entity_reference/lib/Drupal/entity_reference/EntityReferenceController.php
@@ -79,7 +79,7 @@ public function handleAutocomplete(Request $request, $type, $field_name, $entity
 
     $field_definition = $definitions[$field_name];
     $access_controller = $this->entityManager()->getAccessController($entity_type);
-    if ($field_definition->getType() != 'entity_reference' || !$access_controller->fieldAccess('edit', $field_definition)) {
+    if ($field_definition->getTypeId() != 'entity_reference' || !$access_controller->fieldAccess('edit', $field_definition)) {
       throw new AccessDeniedHttpException();
     }
 
diff --git a/core/modules/field/field.views.inc b/core/modules/field/field.views.inc
index c142163..f9d0f95 100644
--- a/core/modules/field/field.views.inc
+++ b/core/modules/field/field.views.inc
@@ -112,7 +112,7 @@ function field_views_field_default_views_data(FieldConfigInterface $field) {
   $data = array();
 
   // Check the field type is available.
-  if (!\Drupal::service('plugin.manager.field.field_type')->getDefinition($field->getType())) {
+  if (!\Drupal::service('plugin.manager.field.field_type')->getDefinition($field->getTypeId())) {
     return $data;
   }
   // Check the field has instances.
diff --git a/core/modules/field/lib/Drupal/field/Entity/FieldConfig.php b/core/modules/field/lib/Drupal/field/Entity/FieldConfig.php
index 7281d7e..e5de951 100644
--- a/core/modules/field/lib/Drupal/field/Entity/FieldConfig.php
+++ b/core/modules/field/lib/Drupal/field/Entity/FieldConfig.php
@@ -511,7 +511,7 @@ public function getName() {
   /**
    * {@inheritdoc}
    */
-  public function getType() {
+  public function getTypeId() {
     return $this->type;
   }
 
@@ -762,7 +762,7 @@ public function getMainPropertyName() {
    */
   protected function getFieldItemClass() {
     $type_definition = \Drupal::typedDataManager()
-      ->getDefinition('field_item:' . $this->getType());
+      ->getDefinition('field_item:' . $this->getTypeId());
     return $type_definition['class'];
   }
 
diff --git a/core/modules/field/lib/Drupal/field/Entity/FieldInstanceConfig.php b/core/modules/field/lib/Drupal/field/Entity/FieldInstanceConfig.php
index 46d8de1..7f8513b 100644
--- a/core/modules/field/lib/Drupal/field/Entity/FieldInstanceConfig.php
+++ b/core/modules/field/lib/Drupal/field/Entity/FieldInstanceConfig.php
@@ -490,7 +490,7 @@ public function getName() {
   /**
    * {@inheritdoc}
    */
-  public function getType() {
+  public function getTypeId() {
     return $this->field->type;
   }
 
@@ -719,7 +719,7 @@ public function isComputed() {
   public function getClass() {
     // Derive list class from the field type.
     $type_definition = \Drupal::service('plugin.manager.field.field_type')
-      ->getDefinition($this->getType());
+      ->getDefinition($this->getTypeId());
     return $type_definition['list_class'];
   }
 
diff --git a/core/modules/field/lib/Drupal/field/FieldInfo.php b/core/modules/field/lib/Drupal/field/FieldInfo.php
index 808a31b..af17a99 100644
--- a/core/modules/field/lib/Drupal/field/FieldInfo.php
+++ b/core/modules/field/lib/Drupal/field/FieldInfo.php
@@ -523,7 +523,7 @@ function getInstance($entity_type, $bundle, $field_name) {
    */
   public function prepareField(FieldConfigInterface $field) {
     // Make sure all expected field settings are present.
-    $field->settings += $this->fieldTypeManager->getDefaultSettings($field->getType());
+    $field->settings += $this->fieldTypeManager->getDefaultSettings($field->getTypeId());
 
     return $field;
   }
@@ -539,7 +539,7 @@ public function prepareField(FieldConfigInterface $field) {
    */
   public function prepareInstance(FieldInstanceConfigInterface $instance) {
     // Make sure all expected instance settings are present.
-    $instance->settings += $this->fieldTypeManager->getDefaultInstanceSettings($instance->getType());
+    $instance->settings += $this->fieldTypeManager->getDefaultInstanceSettings($instance->getTypeId());
 
     return $instance;
   }
diff --git a/core/modules/field/lib/Drupal/field/Plugin/views/field/Field.php b/core/modules/field/lib/Drupal/field/Plugin/views/field/Field.php
index 0f6ceb6..5143961 100644
--- a/core/modules/field/lib/Drupal/field/Plugin/views/field/Field.php
+++ b/core/modules/field/lib/Drupal/field/Plugin/views/field/Field.php
@@ -328,7 +328,7 @@ protected function defineOptions() {
 
     // defineOptions runs before init/construct, so no $this->field_info
     $field = field_info_field($this->definition['entity_type'], $this->definition['field_name']);
-    $field_type = \Drupal::service('plugin.manager.field.field_type')->getDefinition($field->getType());
+    $field_type = \Drupal::service('plugin.manager.field.field_type')->getDefinition($field->getTypeId());
     $column_names = array_keys($field->getColumns());
     $default_column = '';
     // Try to determine a sensible default.
@@ -400,7 +400,7 @@ public function buildOptionsForm(&$form, &$form_state) {
     parent::buildOptionsForm($form, $form_state);
 
     $field = $this->field_info;
-    $formatters = $this->formatterPluginManager->getOptions($field->getType());
+    $formatters = $this->formatterPluginManager->getOptions($field->getTypeId());
     $column_names = array_keys($field->getColumns());
 
     // If this is a multiple value field, add its options.
diff --git a/core/modules/field/tests/modules/field_test/field_test.field.inc b/core/modules/field/tests/modules/field_test/field_test.field.inc
index 79b57a3..a7a988c 100644
--- a/core/modules/field/tests/modules/field_test/field_test.field.inc
+++ b/core/modules/field/tests/modules/field_test/field_test.field.inc
@@ -23,7 +23,7 @@ function field_test_field_widget_info_alter(&$info) {
  * Implements hook_field_config_update_forbid().
  */
 function field_test_field_config_update_forbid(FieldConfigInterface $field, FieldConfigInterface $prior_field) {
-  if ($field->getType() == 'test_field' && $field->getSetting('unchangeable') != $prior_field->getSetting('unchangeable')) {
+  if ($field->getTypeId() == 'test_field' && $field->getSetting('unchangeable') != $prior_field->getSetting('unchangeable')) {
     throw new FieldConfigUpdateForbiddenException("field_test 'unchangeable' setting cannot be changed'");
   }
 }
diff --git a/core/modules/field_ui/lib/Drupal/field_ui/DisplayOverviewBase.php b/core/modules/field_ui/lib/Drupal/field_ui/DisplayOverviewBase.php
index 2deca15..51215de 100644
--- a/core/modules/field_ui/lib/Drupal/field_ui/DisplayOverviewBase.php
+++ b/core/modules/field_ui/lib/Drupal/field_ui/DisplayOverviewBase.php
@@ -268,7 +268,7 @@ protected function buildFieldRow(FieldDefinitionInterface $field_definition, Ent
       '#region_callback' => array($this, 'getRowRegion'),
       '#js_settings' => array(
         'rowHandler' => 'field',
-        'defaultPlugin' => $this->getDefaultPlugin($field_definition->getType()),
+        'defaultPlugin' => $this->getDefaultPlugin($field_definition->getTypeId()),
       ),
       'human_name' => array(
         '#markup' => check_plain($label),
@@ -305,7 +305,7 @@ protected function buildFieldRow(FieldDefinitionInterface $field_definition, Ent
         '#type' => 'select',
         '#title' => $this->t('Plugin for @title', array('@title' => $label)),
         '#title_display' => 'invisible',
-        '#options' => $this->getPluginOptions($field_definition->getType()),
+        '#options' => $this->getPluginOptions($field_definition->getTypeId()),
         '#default_value' => $display_options ? $display_options['type'] : 'hidden',
         '#parents' => array('fields', $field_name, 'type'),
         '#attributes' => array('class' => array('field-plugin-type')),
diff --git a/core/modules/field_ui/lib/Drupal/field_ui/Form/FieldEditForm.php b/core/modules/field_ui/lib/Drupal/field_ui/Form/FieldEditForm.php
index 3739368..b473168 100644
--- a/core/modules/field_ui/lib/Drupal/field_ui/Form/FieldEditForm.php
+++ b/core/modules/field_ui/lib/Drupal/field_ui/Form/FieldEditForm.php
@@ -145,7 +145,7 @@ public function buildForm(array $form, array &$form_state, FieldInstanceConfigIn
 
     // Build the non-configurable field values.
     $form['field']['field_name'] = array('#type' => 'value', '#value' => $field->getName());
-    $form['field']['type'] = array('#type' => 'value', '#value' => $field->getType());
+    $form['field']['type'] = array('#type' => 'value', '#value' => $field->getTypeId());
     $form['field']['module'] = array('#type' => 'value', '#value' => $field->module);
 
     // Add settings provided by the field module. The field module is
diff --git a/core/modules/file/file.module b/core/modules/file/file.module
index 3843be9..0093e27 100644
--- a/core/modules/file/file.module
+++ b/core/modules/file/file.module
@@ -1921,7 +1921,7 @@ function file_get_file_references(File $file, $field = NULL, $age = EntityStorag
     foreach ($return as $field_name => $data) {
       foreach (array_keys($data) as $entity_type_id) {
         $current_field = field_info_field($entity_type_id, $field_name);
-        if (($field_type && $current_field->getType() != $field_type) || ($field && $field->uuid() != $current_field->uuid())) {
+        if (($field_type && $current_field->getTypeId() != $field_type) || ($field && $field->uuid() != $current_field->uuid())) {
           unset($return[$field_name][$entity_type_id]);
         }
       }
diff --git a/core/modules/migrate/lib/Drupal/migrate/Plugin/migrate/destination/EntityContentBase.php b/core/modules/migrate/lib/Drupal/migrate/Plugin/migrate/destination/EntityContentBase.php
index 4feee21..25030dc 100644
--- a/core/modules/migrate/lib/Drupal/migrate/Plugin/migrate/destination/EntityContentBase.php
+++ b/core/modules/migrate/lib/Drupal/migrate/Plugin/migrate/destination/EntityContentBase.php
@@ -84,7 +84,7 @@ public function import(Row $row, array $old_destination_id_values = array()) {
         }
       }
       foreach ($instances as $field_name => $instance) {
-        $field_type = $instance->getType();
+        $field_type = $instance->getTypeId();
         if ($this->migrateEntityFieldPluginManager->getDefinition($field_type)) {
           $destination_value = $this->migrateEntityFieldPluginManager->createInstance($field_type)->import($instance, $row->getDestinationProperty($field_name));
           // @TODO: check for NULL return? Add an unset to $row? Maybe needed in
diff --git a/core/modules/system/lib/Drupal/system/Tests/Entity/EntityFieldTest.php b/core/modules/system/lib/Drupal/system/Tests/Entity/EntityFieldTest.php
index 61c8c87..227b2d2 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Entity/EntityFieldTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Entity/EntityFieldTest.php
@@ -355,9 +355,9 @@ protected function checkIntrospection($entity_type) {
     // Test getting metadata upfront. The entity types used for this test have
     // a default bundle that is the same as the entity type.
     $definitions = \Drupal::entityManager()->getFieldDefinitions($entity_type, $entity_type);
-    $this->assertEqual($definitions['name']->getType(), 'string', $entity_type .': Name field found.');
-    $this->assertEqual($definitions['user_id']->getType(), 'entity_reference', $entity_type .': User field found.');
-    $this->assertEqual($definitions['field_test_text']->getType(), 'text', $entity_type .': Test-text-field field found.');
+    $this->assertEqual($definitions['name']->getTypeId(), 'string', $entity_type .': Name field found.');
+    $this->assertEqual($definitions['user_id']->getTypeId(), 'entity_reference', $entity_type .': User field found.');
+    $this->assertEqual($definitions['field_test_text']->getTypeId(), 'text', $entity_type .': Test-text-field field found.');
 
     // Test deriving further metadata.
     $this->assertTrue($definitions['name'] instanceof FieldDefinitionInterface);
diff --git a/core/modules/taxonomy/lib/Drupal/taxonomy/Controller/TermAutocompleteController.php b/core/modules/taxonomy/lib/Drupal/taxonomy/Controller/TermAutocompleteController.php
index ab1db7d..cf96c30 100644
--- a/core/modules/taxonomy/lib/Drupal/taxonomy/Controller/TermAutocompleteController.php
+++ b/core/modules/taxonomy/lib/Drupal/taxonomy/Controller/TermAutocompleteController.php
@@ -110,7 +110,7 @@ public function autocomplete(Request $request, $entity_type, $field_name) {
     $tags_typed = $request->query->get('q');
 
     // Make sure the field exists and is a taxonomy field.
-    if (!($field = $this->fieldInfo->getField($entity_type, $field_name)) || $field->getType() !== 'taxonomy_term_reference') {
+    if (!($field = $this->fieldInfo->getField($entity_type, $field_name)) || $field->getTypeId() !== 'taxonomy_term_reference') {
       // Error string. The JavaScript handler will realize this is not JSON and
       // will display it as debugging information.
       return new Response(t('Taxonomy field @field_name not found.', array('@field_name' => $field_name)), 403);
diff --git a/core/tests/Drupal/Tests/Core/Entity/FieldDefinitionTest.php b/core/tests/Drupal/Tests/Core/Entity/FieldDefinitionTest.php
index 9637ccb..f901da2 100644
--- a/core/tests/Drupal/Tests/Core/Entity/FieldDefinitionTest.php
+++ b/core/tests/Drupal/Tests/Core/Entity/FieldDefinitionTest.php
@@ -116,7 +116,7 @@ public function testFieldDescription() {
    */
   public function testFieldType() {
     $definition = FieldDefinition::create($this->fieldType);
-    $this->assertEquals($this->fieldType, $definition->getType());
+    $this->assertEquals($this->fieldType, $definition->getTypeId());
   }
 
   /**