diff --git a/core/modules/field/src/Entity/FieldInstanceConfig.php b/core/modules/field/src/Entity/FieldInstanceConfig.php
index be443ef..0c1db07 100644
--- a/core/modules/field/src/Entity/FieldInstanceConfig.php
+++ b/core/modules/field/src/Entity/FieldInstanceConfig.php
@@ -254,7 +254,8 @@ public function __construct(array $values, $entity_type = 'field_instance_config
     }
 
     // Discard the 'field_type' entry that is added in config records to ease
-    // schema generation and data altering for storage. See self::toArray().
+    // schema generation and data altering for storage.
+    // @see Drupal\field\Entity\FieldInstanceConfig::toArray().
     unset($values['field_type']);
 
     parent::__construct($values, $entity_type);
diff --git a/core/modules/options/src/Plugin/Field/FieldType/ListFloatItem.php b/core/modules/options/src/Plugin/Field/FieldType/ListFloatItem.php
index 1b2d323..e0ba02d 100644
--- a/core/modules/options/src/Plugin/Field/FieldType/ListFloatItem.php
+++ b/core/modules/options/src/Plugin/Field/FieldType/ListFloatItem.php
@@ -97,7 +97,6 @@ public static function simplifyAllowedValues(array $structured_values) {
     $values = array();
     foreach ($structured_values as $item) {
       // Nested elements are embedded in the label.
-      // See ListItemBase::structureAllowedValues().
       if (is_array($item['label'])) {
         $item['label'] = static::simplifyAllowedValues($item['label']);
       }
diff --git a/core/modules/options/src/Plugin/Field/FieldType/ListItemBase.php b/core/modules/options/src/Plugin/Field/FieldType/ListItemBase.php
index e13c31e..471c462 100644
--- a/core/modules/options/src/Plugin/Field/FieldType/ListItemBase.php
+++ b/core/modules/options/src/Plugin/Field/FieldType/ListItemBase.php
@@ -267,13 +267,14 @@ public static function settingsFromConfigData(array $settings) {
    * @return array
    *   Allowed values were the array key is the 'value' value, the value is
    *   the 'label' value.
+   *
+   * @see Drupal\options\Plugin\Field\FieldType\ListItemBase::structureAllowedValues()
    */
   protected static function simplifyAllowedValues(array $structured_values) {
     $values = array();
     foreach ($structured_values as $item) {
       if (is_array($item['label'])) {
         // Nested elements are embedded in the label.
-        // See structureAllowedValues().
         $item['label'] = static::simplifyAllowedValues($item['label']);
       }
       $values[$item['value']] = $item['label'];
@@ -291,6 +292,8 @@ protected static function simplifyAllowedValues(array $structured_values) {
    * @return array
    *   Array of items with a 'value' and 'label' key each for the allowed
    *   values.
+   *
+   * @see Drupal\options\Plugin\Field\FieldType\ListItemBase::simplifyAllowedValues()
    */
   protected static function structureAllowedValues(array $values) {
     $structured_values = array();