java - Why does LinkedHashSet<E> extend HashSet<e> and implement Set<E>

Question

Opened a LinkedHashSet source code today and found some interesting thing:

public class LinkedHashSet<E>
    extends HashSet<E>
    implements Set<E>, Cloneable, java.io.Serializable {

The question is: why do they need both "extends HashSet" and "implements Set" when HashSet already is the Set?

Answer 1

I've asked Josh Bloch, and he informs me that it was a mistake. He used to think, long ago, that there was some value in it, but he since "saw the light". Clearly JDK maintainers haven't considered this to be worth backing out later.