About Question com.enthuware.ets.scjp.v6.2.83 :

[TwistedLizard]

From the explanation:

Only Map has values() method. This method returns a Set of values stored in the Map.

Is this an error?

A Set contains no duplicate elements. Although the keys of a Map cannot contain duplicates, the values can. Hence, Map.values() can't return a Set, it returns a Collection.

[admin]

You are right. Fixed.
thank you for your feedback!
Paul.