I've nicked the phrase minimal public interface from a book called 'Object-Oriented Design Heuristics' by Arthur Riel. He says: ‘If the classes that a developer designs and implements are to be reused by other developers in other applications, it is often useful to provide a common minimal public interface. This minimal public interface consists of functionality that can be reasonably expected from each and every class.’

Bill Venners has also written an article on the topic of minimal public interfaces. It is entitled 'The canonical object idiom'. You will find it at http://www.javaworld.com/javaworld/jw-10-1998/jw-10-techniques.html