Is 'Configuration' an Interface or Class in hibernate?

[Kamal Saini]

I have read in 'Hibernate in Action' book that 'Configuration' is an interface. But then below that I saw lines of code like :

Configuration cfg = new Configuration();
SessionFactory sessionFactory =
cfg.configure().buildSessionFactory();

Can someone clear my confusion:
If Configuration is an interface then how we can instantiate it like above code?
Or there are two things in Hibernate one is Configuration class and one is Configuration Interface?

[Manuel Petermann]

javadocs
Its a Class not an Interface.
Maybe it was an Interface in the past. Hibernate isnt very api compatible between versions.

[Kamal Saini]

Thanks, Manuel, For the clarification.