How to get 100 random elements from HashSet in Java?

I have a HashSet in which I have 10000 elements. I want to extract random 100 elements from that HashSet. So I thought I can use shuffle on the set but it doesn't work.

Set<String> users = new HashSet<String>();

// for randomness, but this doesn't work
Collections.shuffle(users, new Random(System.nanoTime()));  

// and use for loop to get 100 elements

I cannot use shuffle now, is there any other best way to get 100 random elements from HashSet in Java?