add file header

bubble-server/src/main/java/bubble/resources/cloud/NetworkBackupKeysResource.java

@@ -1,3 +1,7 @@
+/**
+ * Copyright (c) 2020 Bubble, Inc.  All rights reserved.
+ * For personal (non-commercial) use, see license: https://getbubblenow.com/bubble-license/
+ */
 package bubble.resources.cloud;
 
 import bubble.dao.account.message.AccountMessageDAO;