1Z0-829 OCP Java
17 Book, Chapter 7, page 396 (Casting interfaces section).
The last paragraph contains a sentence that states: "[..]For example, if the Wolf interface
is marked final on line 3, then line 8 no longer compiles."
In the example, Wolf is actually a class that implements an interface, hence it should be referred to as a class. Not to mention that a final interface doesn't make sense.