Cannot find symbol - method iterator()

Question

I'm unsure of why I am getting an error for 'cannot find symbol - method iterator' in my public void print() method. I have imported the relevant package and it still wont work, thank you in advance for any help :)

import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;

public class Thesaurus
{
    private HashMap<String, HashSet<String>> synonyms; 

public Thesaurus()
{
    HashMap<String, String> synonyms = new HashMap<String, String>();
}

public String populate()
{
  HashSet<String> synonyms = new HashSet<String>();
  synonyms.add("happy");
  synonyms.add("joyful");
  synonyms.add("contented");
  synonyms.add("cheerful");
  
  synonyms = new HashSet<>();
  synonyms.add("angry");
  synonyms.add("annoyed");
  synonyms.add("vexed");
}

public void print()
{
   Iterator<String> s = synonyms.iterator();
   while(s.hasNext()){
       System.out.println (s.next());
              
}
}}