diff -u b/core/modules/migrate/src/Entity/MigrationGroup.php b/core/modules/migrate/src/Entity/MigrationGroup.php
--- b/core/modules/migrate/src/Entity/MigrationGroup.php
+++ b/core/modules/migrate/src/Entity/MigrationGroup.php
@@ -23,8 +23,7 @@
  *   },
  *   entity_keys = {
  *     "id" = "id",
- *     "label" = "label",
- *     "weight" = "weight"
+ *     "label" = "label"
  *   }
  * )
  */
diff -u b/core/modules/migrate/src/Tests/MigrationGroupTest.php b/core/modules/migrate/src/Tests/MigrationGroupTest.php
--- b/core/modules/migrate/src/Tests/MigrationGroupTest.php
+++ b/core/modules/migrate/src/Tests/MigrationGroupTest.php
@@ -10,7 +10,6 @@
 use Drupal\migrate\Entity\MigrationInterface;
 use Drupal\migrate\Entity\MigrationGroupInterface;
 use Drupal\simpletest\WebTestBase;
-use Drupal\Component\Utility\SafeMarkup;
 
 /**
  * Test migration groups.
@@ -21,6 +20,9 @@
 
   public static $modules = array('migrate');
 
+  /**
+   * {@inheritdoc}
+   */
   protected function setUp() {
     $this->strictConfigSchema = FALSE;
     parent::setUp();