Fatal error: Uncaught Error: Class "Drupal\migrate\Plugin\migrate\source\SqlBase" not found in /home/www/drupal8/test/modules/migrate_plus/migrate_example/src/Plugin/migrate/source/BeerNode.php:15 Stack trace: #0 {main} thrown in /home/www/drupal8/test/modules/migrate_plus/migrate_example/src/Plugin/migrate/source/BeerNode.php on line 15