CCNA, CCNP, MCSA, CCNA Final Exam, All Answer Test Module With 100/100

I'm having trouble accessing extended protocol buffer members. Here is the scenario: Message Foo { optional int i = 1; } message Bar { extend Foo { optional int j = 10001; } } I don't have the Bar message within any of my other protos. How can I get Bar.j in Java? All examples I've found require a Bar within a message. Thanks!