.../Drupal/Core/Config/Entity/ConfigEntityBundleBase.php    |  6 +++---
 core/lib/Drupal/Core/Entity/BundleEntityFormBase.php        | 13 +++++++++----
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/core/lib/Drupal/Core/Config/Entity/ConfigEntityBundleBase.php b/core/lib/Drupal/Core/Config/Entity/ConfigEntityBundleBase.php
index 0d1bbf2..49d7964 100644
--- a/core/lib/Drupal/Core/Config/Entity/ConfigEntityBundleBase.php
+++ b/core/lib/Drupal/Core/Config/Entity/ConfigEntityBundleBase.php
@@ -105,7 +105,7 @@ public static function postDelete(EntityStorageInterface $storage, array $entiti
    * {@inheritdoc}
    *
    * Ensure that config entities which are bundles of other entities cannot have
-   * their id be renamed.
+   * their ID changed.
    */
   public function preSave(EntityStorageInterface $storage) {
     $bundle_type = $this->getEntityType();
@@ -114,10 +114,10 @@ public function preSave(EntityStorageInterface $storage) {
     if (!empty($bundle_of)) {
       /* @var \Drupal\Core\Entity\DynamicallyFieldableEntityStorageInterface $entity_storage */
       $entity_storage = \Drupal::entityManager()->getStorage($bundle_of);
-      assert($entity_storage instanceof DynamicallyFieldableEntityStorageInterface);
+      assert('$entity_storage instanceof DynamicallyFieldableEntityStorageInterface');
 
       if ($entity_storage->hasData()) {
-        throw new ConfigNameException(t("The name of this @bundle cannot be changed, because @content content already exists.", [
+        throw new ConfigNameException(t("The machine name of this @bundle cannot be changed, because @content content already exists.", [
           '@bundle' => $bundle_type->getLabel(),
           '@content' => $this->entityManager()->getDefinition($bundle_of)->getLabel(),
         ]));
diff --git a/core/lib/Drupal/Core/Entity/BundleEntityFormBase.php b/core/lib/Drupal/Core/Entity/BundleEntityFormBase.php
index e91eae7..78556fa 100644
--- a/core/lib/Drupal/Core/Entity/BundleEntityFormBase.php
+++ b/core/lib/Drupal/Core/Entity/BundleEntityFormBase.php
@@ -2,22 +2,27 @@
 
 /**
  * @file
- * Contains BundleEntityFormBase.
+ * Contains \Drupal\Core\Entity\BundleEntityFormBase.
  */
 
 namespace Drupal\Core\Entity;
 
-
 /**
  * Class BundleEntityFormBase is a base form for bundle config entities.
  */
 class BundleEntityFormBase extends EntityForm {
 
   /**
-   * Protect the id element from updates if needed.
+   * Protects the bundle entity's ID property's form element against changes.
    *
    * This method is assumed to be called on a completely built entity form,
-   * included an element for the entity id.
+   * including a form element for the bundle config entity's ID property.
+   *
+   * @param array $form
+   *   The completely built entity bundle form array.
+   *
+   * @return array
+   *   The updated entity bundle form array.
    */
   protected function protectBundleIdElement(array $form) {
     $entity = $this->getEntity();