CODE EXAMPLE FOR JAVA

Which of the following is an example of a Method reference?

public static void main(String[] args) {

 Set<Integer> set = new TreeSet<Integer>();
 set.add(3);
 set.add((int)3.0);
 set.add(2);
 set.add(2);
 set.add(new Integer(2));
 set.add(Integer.parseInt("2"));
 
 System.out.println(set);
}