diff --git a/core/modules/book/lib/Drupal/book/Form/BookOutlineForm.php b/core/modules/book/lib/Drupal/book/Form/BookOutlineForm.php
index eb5f5fc..120afcd 100644
--- a/core/modules/book/lib/Drupal/book/Form/BookOutlineForm.php
+++ b/core/modules/book/lib/Drupal/book/Form/BookOutlineForm.php
@@ -15,7 +15,7 @@
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
- * @TODO: class def docblock 
+ * @TODO: class def docblock
  */
 class BookOutlineForm implements ControllerInterface, FormInterface {
 
@@ -23,7 +23,7 @@ class BookOutlineForm implements ControllerInterface, FormInterface {
 
   /**
    * This method lets us inject the services this class needs.
-   * 
+   *
    * Only inject services that are actually needed. Which services
    * are needed will vary by the controller.
    */
@@ -127,4 +127,3 @@ public function submitForm(array &$form, array &$form_state) {
     }
   }
 }
-?>
\ No newline at end of file