diff --git a/core/modules/book/tests/src/Kernel/Plugin/migrate/source/d6/BookTest.php b/core/modules/book/tests/src/Kernel/Plugin/migrate/source/d6/BookTest.php
index f8a362eef2..25d0906a36 100644
--- a/core/modules/book/tests/src/Kernel/Plugin/migrate/source/d6/BookTest.php
+++ b/core/modules/book/tests/src/Kernel/Plugin/migrate/source/d6/BookTest.php
@@ -13,7 +13,7 @@ class BookTest extends MigrateSqlSourceTestBase {
   /**
    * {@inheritdoc}
    */
-  public static $modules = ['user', 'node', 'book', 'migrate_drupal'];
+  public static $modules = ['book', 'migrate_drupal', 'node'];
 
   /**
    * {@inheritdoc}
diff --git a/core/modules/migrate_drupal/src/Plugin/migrate/source/ContentEntity.php b/core/modules/migrate_drupal/src/Plugin/migrate/source/ContentEntity.php
index e087d369d0..f9a0420a69 100644
--- a/core/modules/migrate_drupal/src/Plugin/migrate/source/ContentEntity.php
+++ b/core/modules/migrate_drupal/src/Plugin/migrate/source/ContentEntity.php
@@ -13,7 +13,31 @@
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
- * Content entity source from the current version of Drupal.
+ * Source plugin to get content entities from the current version of Drupal.
+ *
+ * Available configuration keys:
+ * - bundle: (optional) String, if the entity type is bundleable, only return
+ *   entities of this bundle.
+ * - exclude_translations: (optional) Boolean, indicates if the entity
+ *   translations should be excluded, default to FALSE.
+ *
+ * Examples:
+ *
+ * This will return all nodes, from every bundles (if this entity type is
+ * bundleable) and every translations (if this entity type is translatable).
+ * @code
+ * source:
+ *   plugin: content_entity:node
+ * @endcode
+ *
+ * This will only return nodes of type 'article' bundle in their default
+ * language.
+ * @code
+ * source:
+ *   plugin: content_entity:node
+ *   bundle: article
+ *   exclude_translations: true
+ * @endcode
  *
  * @MigrateSource(
  *   id = "content_entity",
diff --git a/core/modules/migrate_drupal/tests/src/Kernel/Plugin/migrate/source/ContentEntityTest.php b/core/modules/migrate_drupal/tests/src/Kernel/Plugin/migrate/source/ContentEntityTest.php
index 0607b7535a..2fa1d321fb 100755
--- a/core/modules/migrate_drupal/tests/src/Kernel/Plugin/migrate/source/ContentEntityTest.php
+++ b/core/modules/migrate_drupal/tests/src/Kernel/Plugin/migrate/source/ContentEntityTest.php
@@ -109,8 +109,8 @@ protected function setUp() {
     ConfigurableLanguage::createFromLangcode('fr')->save();
 
     // Create article content type.
-    $nodeType = NodeType::create(['type' => $this->bundle, 'name' => 'Article']);
-    $nodeType->save();
+    $node_type = NodeType::create(['type' => $this->bundle, 'name' => 'Article']);
+    $node_type->save();
 
     // Create a vocabulary.
     $vocabulary = Vocabulary::create([
@@ -334,7 +334,6 @@ public function testTermSource() {
       'exclude_translations' => TRUE,
       'bundle' => $this->vocabulary,
     ];
-    $taxonomy_term_storage = $this->container->get('entity_type.manager')->getStorage('taxonomy_term');
     $migration = $this->migrationPluginManager->createStubMigration($this->migrationDefinition('content_entity:taxonomy_term'));
     $term_source = $this->sourcePluginManager->createInstance('content_entity:taxonomy_term', $configuration, $migration);
     $this->assertSame('taxonomy term entities', $term_source->__toString());
@@ -350,16 +349,15 @@ public function testTermSource() {
     $values = $term_source->current()->getSource();
     $this->assertEquals($this->vocabulary, $values['vid'][0]['target_id']);
     $this->assertEquals(1, $values['tid']);
-    $parents = $taxonomy_term_storage->loadParents($values['tid']);
-    $this->assertEmpty($parents);
+    // @TODO: Add test coverage for parent in
+    // https://www.drupal.org/project/drupal/issues/2940198
     $this->assertEquals('Apples', $values['name'][0]['value']);
     $term_source->next();
     $values = $term_source->current()->getSource();
     $this->assertEquals($this->vocabulary, $values['vid'][0]['target_id']);
     $this->assertEquals(2, $values['tid']);
-    $parents = $taxonomy_term_storage->loadParents($values['tid']);
-    $parent = reset($parents);
-    $this->assertEquals(1, $parent->id());
+    // @TODO: Add test coverage for parent in
+    // https://www.drupal.org/project/drupal/issues/2940198
     $this->assertEquals('Granny Smith', $values['name'][0]['value']);
   }