diff --git a/core/lib/Drupal/Core/Entity/EntityReferenceSelection/SelectionPluginBase.php b/core/lib/Drupal/Core/Entity/EntityReferenceSelection/SelectionPluginBase.php
index 6e04dcd..0dcbd54 100644
--- a/core/lib/Drupal/Core/Entity/EntityReferenceSelection/SelectionPluginBase.php
+++ b/core/lib/Drupal/Core/Entity/EntityReferenceSelection/SelectionPluginBase.php
@@ -22,7 +22,6 @@
    *   The plugin_id for the plugin instance.
    * @param mixed $plugin_definition
    *   The plugin implementation definition.
-   *   The current user.
    */
   public function __construct(array $configuration, $plugin_id, $plugin_definition) {
     parent::__construct($configuration, $plugin_id, $plugin_definition);
@@ -35,7 +34,6 @@ public function __construct(array $configuration, $plugin_id, $plugin_definition
   public function defaultConfiguration() {
     return [
       'target_type' => NULL,
-      'handler' => NULL,
       'handler_settings' => $this->defaultHandlerSettings(),
     ];
   }
@@ -68,6 +66,7 @@ public function calculateDependencies() {
    * Returns the default handler settings.
    *
    * @return array
+   *   An associative array of selection handler settings.
    *
    * @todo Add this to SelectionInterface in Drupal 9.0.x.
    */
diff --git a/core/lib/Drupal/Core/Entity/EntityReferenceSelection/SelectionTrait.php b/core/lib/Drupal/Core/Entity/EntityReferenceSelection/SelectionTrait.php
index 16eead0..1d7947d 100644
--- a/core/lib/Drupal/Core/Entity/EntityReferenceSelection/SelectionTrait.php
+++ b/core/lib/Drupal/Core/Entity/EntityReferenceSelection/SelectionTrait.php
@@ -8,7 +8,7 @@
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
- * Provides common methods and inject services for core selection handlers.
+ * Provides common methods and injects services for core selection handlers.
  */
 trait SelectionTrait {
 
diff --git a/core/lib/Drupal/Core/Entity/Plugin/EntityReferenceSelection/DefaultSelection.php b/core/lib/Drupal/Core/Entity/Plugin/EntityReferenceSelection/DefaultSelection.php
index 4064e15..e2ff031 100644
--- a/core/lib/Drupal/Core/Entity/Plugin/EntityReferenceSelection/DefaultSelection.php
+++ b/core/lib/Drupal/Core/Entity/Plugin/EntityReferenceSelection/DefaultSelection.php
@@ -47,6 +47,7 @@ public function defaultHandlerSettings() {
       'target_bundles' => NULL,
       'sort' => [
         'field' => '_none',
+        'direction' => 'ASC',
       ],
       'auto_create' => FALSE,
       'auto_create_bundle' => NULL,
@@ -142,11 +143,6 @@ public function buildConfigurationForm(array $form, FormStateInterface $form_sta
       );
 
       if ($selection_handler_settings['sort']['field'] != '_none') {
-        // Merge-in default values.
-        $selection_handler_settings['sort'] += array(
-          'direction' => 'ASC',
-        );
-
         $form['sort']['settings']['direction'] = array(
           '#type' => 'select',
           '#title' => $this->t('Sort direction'),
diff --git a/core/modules/user/src/Plugin/EntityReferenceSelection/UserSelection.php b/core/modules/user/src/Plugin/EntityReferenceSelection/UserSelection.php
index 2b0e411..e5015f0 100644
--- a/core/modules/user/src/Plugin/EntityReferenceSelection/UserSelection.php
+++ b/core/modules/user/src/Plugin/EntityReferenceSelection/UserSelection.php
@@ -86,7 +86,7 @@ public function defaultHandlerSettings() {
     return [
       'filter' => [
         'type' => '_none',
-      ],
+        'role' => NULL,      ],
       'include_anonymous' => TRUE,
     ] + parent::defaultHandlerSettings();
   }
@@ -123,11 +123,6 @@ public function buildConfigurationForm(array $form, FormStateInterface $form_sta
     );
 
     if ($selection_handler_settings['filter']['type'] == 'role') {
-      // Merge in default values.
-      $selection_handler_settings['filter'] += array(
-        'role' => NULL,
-      );
-
       $form['filter']['settings']['role'] = array(
         '#type' => 'checkboxes',
         '#title' => $this->t('Restrict to the selected roles'),