addressed a github issue

Author: scmacdon

javav2/example_code/s3/src/main/java/com/example/s3/express/UserNames.java

@@ -1,3 +1,6 @@
+// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+
 package com.example.s3.express;
 
 public class UserNames {