diff -u b/core/modules/node/src/Plugin/migrate/source/d6/ViewModeBase.php b/core/modules/node/src/Plugin/migrate/source/d6/ViewModeBase.php
--- b/core/modules/node/src/Plugin/migrate/source/d6/ViewModeBase.php
+++ b/core/modules/node/src/Plugin/migrate/source/d6/ViewModeBase.php
@@ -14,7 +14,6 @@
  */
 abstract class ViewModeBase extends DrupalSqlBase {
 
-
   /**
    * {@inheritdoc}
    */
only in patch2:
unchanged:
--- a/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/FieldInstancePerViewMode.php
+++ b/core/modules/migrate_drupal/src/Plugin/migrate/source/d6/FieldInstancePerViewMode.php
@@ -7,6 +7,8 @@
 
 namespace Drupal\migrate_drupal\Plugin\migrate\source\d6;
 
+use Drupal\node\Plugin\migrate\source\d6\ViewModeBase;
+
 /**
  * The field instance per view mode source class.
  *