EMPTY_SET and SingletonSet should implement SortedSet
java.util.Collections.EMPTY_SET and results of java.util.Collections.singleton(Object o) should implement the java.util.SortedSet interface.
This sets guarantee the only ordering of its elements according to any correct Comparator.
I have written an RFE in such a meaning on September 01. 2004, I got an email, acknowledging, that the RFE had been accepted but nothing has happened for 2 months. The RFE hasn't appeared in the bugparade yet.
Is it common to have such as response times from sun? And would you find such a small improvement of API usefull?