diff --git a/core/modules/book/book.views.inc b/core/modules/book/book.views.inc
index 3b3e3a4..2fe6888 100644
--- a/core/modules/book/book.views.inc
+++ b/core/modules/book/book.views.inc
@@ -76,7 +76,6 @@ function book_views_data() {
     'help' => t('The weight of the book page.'),
     'field' => [
       'id' => 'numeric',
-      'click sortable' => TRUE,
     ],
     'sort' => [
       'id' => 'standard',
@@ -88,7 +87,6 @@ function book_views_data() {
     'help' => t('The depth of the book page in the hierarchy; top level books have a depth of 1.'),
     'field' => [
       'id' => 'numeric',
-      'click sortable' => TRUE,
     ],
     'sort' => [
       'id' => 'standard',
@@ -111,14 +109,14 @@ function book_views_data() {
     8 => t('8th parent'),
     9 => t('9th parent'),
   ];
-  foreach ($parents as $i => $parent) {
+  foreach ($parents as $i => $parent_label) {
     $data['book']["p$i"] = [
-      'title' => $parent,
-      'help' => t('The !parent of book node.', ['!parent' => $parent]),
+      'title' => $parent_label,
+      'help' => t('The !parent of book node.', ['!parent' => $parent_label]),
       'relationship' => [
         'base' => 'node',
         'id' => 'standard',
-        'label' => t('Book !parent', ['!parent' => $parent]),
+        'label' => t('Book !parent', ['!parent' => $parent_label]),
       ],
     ];
   }
diff --git a/core/modules/book/src/Plugin/views/argument_default/Root.php b/core/modules/book/src/Plugin/views/argument_default/BookRoot.php
similarity index 89%
rename from core/modules/book/src/Plugin/views/argument_default/Root.php
rename to core/modules/book/src/Plugin/views/argument_default/BookRoot.php
index 7c933e2..3edf45b 100644
--- a/core/modules/book/src/Plugin/views/argument_default/Root.php
+++ b/core/modules/book/src/Plugin/views/argument_default/BookRoot.php
@@ -2,7 +2,7 @@
 
 /**
  * @file
- * Contains Drupal\book\Plugin\views\argument_default\Root.
+ * Contains Drupal\book\Plugin\views\argument_default\BookRoot.
  */
 
 namespace Drupal\book\Plugin\views\argument_default;
@@ -20,7 +20,7 @@
  *   title = @Translation("Book root from current node")
  * )
  */
-class Root extends Node implements ContainerFactoryPluginInterface {
+class BookRoot extends Node implements ContainerFactoryPluginInterface {
 
   /**
    * The node storage controller.
@@ -30,7 +30,7 @@ class Root extends Node implements ContainerFactoryPluginInterface {
   protected $nodeStorage;
 
   /**
-   * Constructs a Drupal\book\Plugin\views\argument_default\Root object.
+   * Constructs a Drupal\book\Plugin\views\argument_default\BookRoot object.
    *
    * @param array $configuration
    *   A configuration array containing information about the plugin instance.