Map Duplicate values Display

import java.util.Collections;

import java.util.HashMap;

import java.util.stream.Collectors;

public class MapDuplicateDisplay {

    public static void main(String[] args) {

HashMap hm=new HashMap<>();

hm.put(12, "twelve");

hm.put(3,"three");

hm.put(1, "four");

hm.put(1,"one");

hm.put(6,"three");

hm.entrySet().stream().filter(duplicates -> Collections.frequency(hm.values(), duplicates.getValue()) >1).collect(Collectors.toList()).forEach(System.out::println);

}
}