gistfile1.java

public class Example {

    public static interface Foo<T extends Bar> {
        T[] getEnumValues();
    }

    public static interface Bar {

    }

    public static class FooImpl implements Foo<FooImpl.BarImpl> {
       public enum BarImpl implements Bar {
           A, B, C;
       }

        @Override
        public BarImpl[] getEnumValues() {
            return BarImpl.values();
        }
    }
}