Fatal error: Uncaught Error: Class "Drupal\rest\Plugin\rest\resource\EntityResource" not found in /home/www/drupal8/test/core/modules/contact/src/Plugin/rest/resource/ContactMessageResource.php:16 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/contact/src/Plugin/rest/resource/ContactMessageResource.php on line 16