Что не так???

if (pair.getValue() != null)
           {
               s.append(pair.getKey() +" = '" + pair.getValue()+"' and ");
           } else {
               s.append("");
           }

boolean allValuesAreNull = params.values().stream().allMatch(Objects::isNull);

            if (allValuesAreNull) {
                return "";
            }

package com.javarush.task.task22.task2208;

import java.util.HashMap;
import java.util.Map;
import java.util.Objects;

/*
Формируем WHERE
*/
public class Solution {
    public static void main(String[] args) {
        Map<String, String> params1 = new HashMap<String,String>();
        params1.put("name","Ivanov");
        params1.put("country","Ukraine");
        params1.put("city","Kiev");
        params1.put("age",null);
        System.out.println(getQuery(params1));
    }
    public static String getQuery(Map<String, String> params)
    {
        StringBuilder s = new StringBuilder();
        for (Map.Entry<String,String> pair : params.entrySet())
        {
            boolean allValuesAreNull = params.values().stream().allMatch(Objects::isNull);

            if (allValuesAreNull) {
                return "";
            }

            if (pair.getValue() != null)
            {
                s.append(pair.getKey() +" = '" + pair.getValue()+"' and ");
            }else {
                s.append(" ");
            }
        }
        s.delete(s.toString().length()-5,s.toString().length());
        return s.toString();
    }
}

params1.put("name",null);
params1.put("country","Ukraine");
params1.put("city",null);
params1.put("age",null);

for (Map.Entry<String,String> pair : params.entrySet())
       {


           if (allValuesAreNull) {
               return "";
           }

           if (pair.getValue() != null) {
               s.append(pair.getKey() + " = '" + pair.getValue() + "' and ");

          }
       }

if (allValuesAreNull) {
    return "";
}