diff --git a/core/lib/Drupal/Core/Entity/Field/FieldItemBase.php b/core/lib/Drupal/Core/Entity/Field/FieldItemBase.php
index c51d5a1..c021c57 100644
--- a/core/lib/Drupal/Core/Entity/Field/FieldItemBase.php
+++ b/core/lib/Drupal/Core/Entity/Field/FieldItemBase.php
@@ -44,6 +44,29 @@ public function getFieldDefinition() {
   }
 
   /**
+   * Returns the array of field settings.
+   *
+   * @return array
+   *   The array of settings.
+   */
+  protected function getFieldSettings() {
+    return $this->getFieldDefinition()->getFieldSettings();
+  }
+
+  /**
+   * Returns the value of a field setting.
+   *
+   * @param string $setting_name
+   *   The setting name.
+   *
+   * @return mixed
+   *   The setting value.
+   */
+  protected function getFieldSetting($setting_name) {
+    return $this->getFieldDefinition()->getFieldSetting($setting_name);
+  }
+
+  /**
    * Overrides \Drupal\Core\TypedData\TypedData::setValue().
    *
    * @param array|null $values
diff --git a/core/modules/telephone/lib/Drupal/telephone/Plugin/field/field_type/TelephoneItem.php b/core/modules/telephone/lib/Drupal/telephone/Plugin/field/field_type/TelephoneItem.php
index c7725d9..d5cce2a 100644
--- a/core/modules/telephone/lib/Drupal/telephone/Plugin/field/field_type/TelephoneItem.php
+++ b/core/modules/telephone/lib/Drupal/telephone/Plugin/field/field_type/TelephoneItem.php
@@ -81,7 +81,7 @@ public function getConstraints() {
       'value' => array(
         'Length' => array(
           'max' => $max_length,
-          'maxMessage' => t('%name: the telephone number may not be longer than @max characters.', array('%name' => $this->getInstance()->label, '@max' => $max_length)),
+          'maxMessage' => t('%name: the telephone number may not be longer than @max characters.', array('%name' => $this->getFieldDefinition()->getFieldLabel(), '@max' => $max_length)),
         )
       ),
     ));
diff --git a/core/modules/text/lib/Drupal/text/Plugin/field/field_type/TextItem.php b/core/modules/text/lib/Drupal/text/Plugin/field/field_type/TextItem.php
index 1c79cf7..40d3325 100644
--- a/core/modules/text/lib/Drupal/text/Plugin/field/field_type/TextItem.php
+++ b/core/modules/text/lib/Drupal/text/Plugin/field/field_type/TextItem.php
@@ -67,7 +67,7 @@ public function getConstraints() {
     $constraint_manager = \Drupal::typedData()->getValidationConstraintManager();
     $constraints = parent::getConstraints();
 
-    if ($max_length = $this->getFieldDefinition()->getFieldSetting('max_length')) {
+    if ($max_length = $this->getFieldSetting('max_length')) {
       $constraints[] = $constraint_manager->create('ComplexData', array(
         'value' => array(
           'Length' => array(
@@ -86,18 +86,17 @@ public function getConstraints() {
    */
   public function settingsForm(array $form, array &$form_state) {
     $element = array();
-    $field = $this->getInstance()->getField();
 
     $element['max_length'] = array(
       '#type' => 'number',
       '#title' => t('Maximum length'),
-      '#default_value' => $field->settings['max_length'],
+      '#default_value' => $this->getFieldSetting('max_length'),
       '#required' => TRUE,
       '#description' => t('The maximum length of the field in characters.'),
       '#min' => 1,
       // @todo: If $has_data, add a validate handler that only allows
       // max_length to increase.
-      '#disabled' => $field->hasData(),
+      '#disabled' => $this->getInstance()->getField()->hasData(),
     );
 
     return $element;
@@ -112,7 +111,7 @@ public function instanceSettingsForm(array $form, array &$form_state) {
     $element['text_processing'] = array(
       '#type' => 'radios',
       '#title' => t('Text processing'),
-      '#default_value' => $this->getInstance()->settings['text_processing'],
+      '#default_value' => $this->getFieldSetting('text_processing'),
       '#options' => array(
         t('Plain text'),
         t('Filtered text (user selects text format)'),
diff --git a/core/modules/text/lib/Drupal/text/Plugin/field/field_type/TextItemBase.php b/core/modules/text/lib/Drupal/text/Plugin/field/field_type/TextItemBase.php
index df9cea0..cf41e9d 100644
--- a/core/modules/text/lib/Drupal/text/Plugin/field/field_type/TextItemBase.php
+++ b/core/modules/text/lib/Drupal/text/Plugin/field/field_type/TextItemBase.php
@@ -74,7 +74,7 @@ public function prepareCache() {
     // Where possible, generate the sanitized version of each field early so
     // that it is cached in the field cache. This avoids the need to look up the
     // field in the filter cache separately.
-    $text_processing = $this->getFieldDefinition()->getFieldSetting('text_processing');
+    $text_processing = $this->getFieldSetting('text_processing');
     if (!$text_processing || filter_format_allowcache($this->get('format')->getValue())) {
       $itemBC = $this->getValue();
       $langcode = $this->getParent()->getParent()->language()->id;
diff --git a/core/modules/text/lib/Drupal/text/Plugin/field/field_type/TextLongItem.php b/core/modules/text/lib/Drupal/text/Plugin/field/field_type/TextLongItem.php
index be86655..9aa06ed 100644
--- a/core/modules/text/lib/Drupal/text/Plugin/field/field_type/TextLongItem.php
+++ b/core/modules/text/lib/Drupal/text/Plugin/field/field_type/TextLongItem.php
@@ -66,7 +66,7 @@ public function instanceSettingsForm(array $form, array &$form_state) {
     $element['text_processing'] = array(
       '#type' => 'radios',
       '#title' => t('Text processing'),
-      '#default_value' => $this->getInstance()->settings['text_processing'],
+      '#default_value' => $this->getFieldSetting('text_processing'),
       '#options' => array(
         t('Plain text'),
         t('Filtered text (user selects text format)'),
diff --git a/core/modules/text/lib/Drupal/text/Plugin/field/field_type/TextWithSummaryItem.php b/core/modules/text/lib/Drupal/text/Plugin/field/field_type/TextWithSummaryItem.php
index 7aecf67..71bc17e 100644
--- a/core/modules/text/lib/Drupal/text/Plugin/field/field_type/TextWithSummaryItem.php
+++ b/core/modules/text/lib/Drupal/text/Plugin/field/field_type/TextWithSummaryItem.php
@@ -108,11 +108,12 @@ public function isEmpty() {
    */
   public function instanceSettingsForm(array $form, array &$form_state) {
     $element = array();
+    $settings = $this->getFieldSettings();
 
     $element['text_processing'] = array(
       '#type' => 'radios',
       '#title' => t('Text processing'),
-      '#default_value' => $this->getInstance()->settings['text_processing'],
+      '#default_value' => $settings['text_processing'],
       '#options' => array(
         t('Plain text'),
         t('Filtered text (user selects text format)'),
@@ -121,7 +122,7 @@ public function instanceSettingsForm(array $form, array &$form_state) {
     $element['display_summary'] = array(
       '#type' => 'checkbox',
       '#title' => t('Summary input'),
-      '#default_value' => $this->getInstance()->settings['display_summary'],
+      '#default_value' => $settings['display_summary'],
       '#description' => t('This allows authors to input an explicit summary, to be displayed instead of the automatically trimmed text when using the "Summary or trimmed" display type.'),
     );