import java.util.*;
public class ShouldNotCompile {

  public static void main(String[] args) {

    ImmutableSet<String> set = new ImmutableSet<String>(new String[]{"1","2"}) {
	private Set<String> elements = new TreeSet<String>();
	public boolean add(String s) {
	  return elements.add(s);
	}
    };
  }
}