При попытке получить данные из БД падает NPE

Создал метод dbstore, который должен создавать базу, если она пуста, извелкать всех пользователей и т.д.

Проблема с методом findAll при попытке добавить пользователя в коллекци. кидает NPE

Создал тесты, в которыйх проверяю это метод, и он кидает эту ошбку. 1. Пользователи в БД есть. 2. Настройки подключения к БД верные. В классе user опущены гетеры и т.п.

public class TestDBSTORE {
@Test
public void whenFindAll() {
    DBStore store = new DBStore();
    assertThat(store.findAll(), is(store.findById(1)));
}
@Test
public void whenIsCredential() {
    DBStore store = new DBStore();
    assertThat(store.isCredential("root", "root"), is(true));
}}

public class User {
private int id;
private String name;
private String login;
private String email;
private Timestamp createDat;
private String password;
private int role;
public User(int id, String name, String login, String email, String  createDate, String password, int role) {
    this.id = id;
    this.name = name;
    this.login = login;
    this.email = email;
    this.createDat = Timestamp.valueOf(createDate.replace("T", " ").replace("Z", ""));
    this.password = password;
    this.role = role;
}
}

public class DBStore implements Store, AutoCloseable {
private static final Logger LOG = LogManager.getLogger(DBStore.class.getName());
private static final BasicDataSource SOURCE = new BasicDataSource();
private static final DBStore INSTANCE = new DBStore();
public DBStore() {
    SOURCE.setDriverClassName("org.postgresql.Driver");
    SOURCE.setUrl("jdbc:postgresql://127.0.0.1:5432/postgres");
    SOURCE.setUsername("postgres");
    SOURCE.setPassword("password");
    SOURCE.setMinIdle(5);
    SOURCE.setMaxIdle(10);
    SOURCE.setMaxOpenPreparedStatements(100);
    createTable();
    if (isEmpty()) {
        addRootUser();
    }
}
public static DBStore getInstance() {
    return INSTANCE;
}
private void addRootUser() {
    try (Connection connection = SOURCE.getConnection();
         PreparedStatement ps = connection.prepareStatement("insert into clients (name, login, email, createDate, password, role) values (?, ?, ?, ?, ?, ?)");
    ) {
        ps.setString(1, "root");
        ps.setString(2, "root");
        ps.setString(3, "root");
        ps.setTimestamp(4, new Timestamp(System.currentTimeMillis()));
        ps.setString(5, "root");
        ps.setInt(6, 0);
        ps.executeQuery();
    } catch (SQLException e) {
        LOG.error(e.getMessage(), e);
    }
}
private boolean isEmpty() {
    int count = 0;
    boolean result = false;
    try (Connection connection = SOURCE.getConnection();
         PreparedStatement ps = connection.prepareStatement("Select count(*) clients");
    ) {
      ResultSet rs = ps.executeQuery();
      while (rs.next()) {
          count = rs.getInt(1);
          if (count == 0) {
              result = true;
              break;
          }
      }
    } catch (SQLException e) {
        LOG.error(e.getMessage(), e);
    }
    return result;
}

private void createTable() {
    try (Connection connection = SOURCE.getConnection()) {
        final PreparedStatement ps = connection.prepareStatement(
                "create table if not exists clients(id serial primary key, name character(2000), login character(2000), email character(2000), createDate timestamp, password character(2000), role integer)"
        );
        ps.execute();
    } catch (SQLException e) {
        LOG.error(e.getMessage(), e);
    }
}
@Override
public boolean add(User user) {
    boolean result = false;
    try (Connection connection = SOURCE.getConnection();
         PreparedStatement ps = connection.prepareStatement("insert into clients (name, login, email, createDate, password, role) values (?, ?, ?, ?, ?, ?)");
    ) {
        ps.setString(1, user.getName());
        ps.setString(2, user.getLogin());
        ps.setString(3, user.getEmail());
        ps.setTimestamp(4, new Timestamp(System.currentTimeMillis()));
        ps.setString(5, user.getPassword());
        ps.setInt(6, user.getRole());
        result = ps.execute();
    } catch (SQLException e) {
        LOG.error(e.getMessage(), e);
    }
    return result;
}
@Override
public boolean update(int id, User user) {
    boolean result = false;
    try (Connection connection = SOURCE.getConnection();
         PreparedStatement ps = connection.prepareStatement("update clients set name = ?, login = ?, email = ?, password = ?, role = ?, createDate = ? where id = ?");
    ) {
        ps.setString(1, user.getName());
        ps.setString(2, user.getLogin());
        ps.setString(3, user.getEmail());
        ps.setString(4, user.getPassword());
        ps.setInt(5, user.getRole());
        ps.setTimestamp(6, new Timestamp(System.currentTimeMillis()));
        ps.setInt(7, id);
        ps.executeUpdate();
        result = true;
    } catch (SQLException e) {
        LOG.error(e.getMessage(), e);
    }
    return result;
}
@Override
public boolean delete(int id) {
    boolean result = false;
    try (Connection connection = SOURCE.getConnection();
         PreparedStatement ps = connection.prepareStatement("delete from clients where id = ?");
    ) {
        ps.setInt(1, id);
        ps.executeUpdate();
        result = true;
    } catch (SQLException e) {
        LOG.error(e.getMessage(), e);
    }
    return result;
}
@Override
public CopyOnWriteArrayList<User> findAll() {
    CopyOnWriteArrayList<User> list = null;
    try (Connection connection = SOURCE.getConnection();
    PreparedStatement ps = connection.prepareStatement("select * from clients");
    ) {
        ResultSet rs = ps.executeQuery();
        while (rs.next()) {
            list.add(this.getByResultSet(rs));
        }
    } catch (SQLException e) {
        LOG.error(e.getMessage(), e);
    }
    return list;
}
private User getByResultSet(ResultSet rs) throws SQLException {
    return new User(
            rs.getInt("id"),
            rs.getString("name"),
            rs.getString("login"),
            rs.getString("email"),
            rs.getString("createdate"),
            rs.getString("password"),
            rs.getInt("role")
    );
}
@Override
public User findById(int id) {
    User user = null;
    try (Connection connection = SOURCE.getConnection();
         PreparedStatement ps = connection.prepareStatement("select * from clients where id = ?");
    ) {
        ps.setInt(1, id);
        ResultSet rs = ps.executeQuery();
        while (rs.next()) {
            user = getByResultSet(rs);
        }
    } catch (SQLException e) {
        LOG.error(e.getMessage(), e);
    }
    return user;
}
public int role(String login, String password) {
   int result = -1;
   try (Connection connection = SOURCE.getConnection();
        PreparedStatement ps = connection.prepareStatement("select * from clients where login = ?");
        ) {
            ps.setString(1, login);
         ResultSet rs = ps.executeQuery();
         while (rs.next()) {
             result = (int) rs.getInt("role");
             break;
         }
   } catch (SQLException e) {
        LOG.error(e.getMessage(), e);
    }
   return result;
}
public boolean isCredential(String login, String password) {
    boolean result = false;
    for (User user: findAll()) {
        if (user.getLogin().equals(login) && user.getID().equals(password)) {
            result = true;
            break;
        }
    }
    return result;
}
@Override
public void close() throws Exception {
    SOURCE.close();
}

}