NullPointer

из 82 строки вылезает нуллпоинтер, почему? я честно понять не могу

package com.javarush.task.task20.task2002;


import java.io.*;
import java.util.*;

/*
Читаем и пишем в файл: JavaRush
*/
public class Solution {
    public static void main(String[] args) {
        //you can find your_file_name.tmp in your TMP directory or adjust outputStream/inputStream according to your file's actual location
        //вы можете найти your_file_name.tmp в папке TMP или исправьте outputStream/inputStream в соответствии с путем к вашему реальному файлу
        try {
            File yourFile = File.createTempFile("your_file_name", null);
            OutputStream outputStream = new FileOutputStream(yourFile);
            InputStream inputStream = new FileInputStream(yourFile);

            JavaRush javaRush = new JavaRush();
            //initialize users field for the javaRush object here - инициализируйте поле users для объекта javaRush тут
            javaRush.save(outputStream);
            outputStream.flush();

            JavaRush loadedObject = new JavaRush();
            loadedObject.load(inputStream);
            //here check that the javaRush object is equal to the loadedObject object - проверьте тут, что javaRush и loadedObject равны

            outputStream.close();
            inputStream.close();

        } catch (IOException e) {
            //e.printStackTrace();
            System.out.println("Oops, something is wrong with my file");
        } catch (Exception e) {
            //e.printStackTrace();
            System.out.println("Oops, something is wrong with the save/load method");
        }
    }

    public static class JavaRush {
        public List<User> users = new ArrayList<>();

        public void save(OutputStream outputStream) throws Exception {
            PrintWriter printWriter = new PrintWriter(outputStream);
            String isUsersPresent = users.isEmpty() ? "yes" : "no";
            printWriter.println(isUsersPresent);
            printWriter.flush();

            users.forEach(s -> {
                StringJoiner stringJoiner = new StringJoiner("_");
                if (s.getCountry() == null) {
                    stringJoiner.add("null");
                } else {
                    stringJoiner.add(s.getCountry().getDisplayName());
                }
                if (s.getBirthDate() == null) {
                    stringJoiner.add("null");
                } else {
                    stringJoiner.add(String.valueOf(s.getBirthDate().getTime()));
                }
                if (s.getFirstName() == null) {
                    stringJoiner.add(null);
                } else {
                    stringJoiner.add(s.getFirstName());
                }
                if (s.getLastName() == null) {
                    stringJoiner.add("null");
                } else {
                    stringJoiner.add(s.getLastName());
                }
                stringJoiner.add(String.valueOf(s.isMale()));
                printWriter.println(stringJoiner.toString());
                printWriter.flush();
            });
            printWriter.close();
        }

        public void load(InputStream inputStream) throws Exception {
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
            if (bufferedReader.readLine().equals("yes")) {
                String line = bufferedReader.readLine();
                String[] tmp = line.split("_");
                User user = new User();
                if (tmp[0].equals("null")) {
                    user.setCountry(null);
                } else {
                    if (tmp[0].equals("Ukraine")) {
                        user.setCountry(User.Country.UKRAINE);
                    } else if (tmp[0].equals("Russia")) {
                        user.setCountry(User.Country.RUSSIA);
                    } else {
                        user.setCountry(User.Country.OTHER);
                    }
                }
                if (tmp[1].equals("null")) {
                    user.setBirthDate(null);
                } else {
                    user.setBirthDate(new Date(Long.parseLong(tmp[1])));
                }
                if (tmp[2].equals("null")) {
                    user.setFirstName(null);
                } else {
                    user.setFirstName(tmp[2]);
                }
                if (tmp[3].equals("null")) {
                    user.setLastName(null);
                } else {
                    user.setLastName(tmp[3]);
                }
                if (tmp[4].equals("true")) {
                    user.setMale(true);
                } else {
                    user.setMale(false);
                }
                users.add(user);
            }
            bufferedReader.close();
        }

        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;

            JavaRush javaRush = (JavaRush) o;

            return users != null ? users.equals(javaRush.users) : javaRush.users == null;

        }

        @Override
        public int hashCode() {
            return users != null ? users.hashCode() : 0;
        }
    }
}