web/modules/custom/example/example.module

@@ -13,5 +13,5 @@ use Drupal\Core\Entity\EntityInterface;
  * Implements hook_entity_view().
  */
 function example_entity_view(array &$build, EntityInterface $entity): void {
-  Drupal::messenger()->addMessage('This is a node.');
+  drupal_set_message(t('This is a node.'));
 }