I was a bit disappointed when I looked at Shiro for the first time. I was expecting a framework that allows me to easily plug into outside authentication services like Microsoft Azure authentication service, AWS authentication service, Google authentication service, Yahoo, OpenID,.....etc.
Shiro should have this functionality of allows the programmer to quick, elegantly implement authentication with an outside provider of authentication services. A good framework should do that in the most easy way for the programmer. Furthermore, changing from one authentication provider to another should be quick.