1. create a gradle fragment project
2. choose login.web as host osgi jar
3. choose login.jsp as override files
4. add Hello World to login.jsp
5.deploy to liferay portal 7.1
6. log in
You will see your custom change.
But when you change your login.jsp agian, and redeploy.
It doesn't work anymore.
The same for Liferay 7 ga5 and ga6.