@Entity
    @Table(name = "user")
    public class User implements model.Entity {

    @Id
    @GeneratedValue
    @Column(name = "userId", nullable = false)
    private int userId;

    @Column(name = "firstName")
    private String firstName;

    @Column(name = "lastName")
    private String lastName;

    @Column(name = "login", nullable = false)
    private String login;

    @Column(name = "password", nullable = false)
    private String password;

    @ManyToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    @JoinColumn(name = "roleId", nullable = false)
    private Set<Role> roleId;

    @Transient
    private String confirmPassword;

    public int getUserId() {
        return userId;
    }

    public void setUserId(int userId) {
        this.userId = userId;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getLogin() {
        return login;
    }

    public void setLogin(String login) {
        this.login = login;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public Set<Role> getRoleId() {
        return roleId;
    }

    public void setRoleId(Set<Role> roleId) {
        this.roleId = roleId;
    }
 }

@Entity
    @Table(name = "role")
    public class Role implements model.Entity {
    @Id
    @GeneratedValue
    @Column(name = "roleId", nullable = false)
    private int roleId;

    @Column(name = "user")
    private boolean user;

    @Column(name = "tutor")
    private boolean tutor;

    @Column(name = "admin")
    private boolean admin;

    public Role() {} //пустой конструктор, чтобы был pojo класс

    public int getRoleId() {
        return roleId;
    }

    public void setRoleId(int roleId) {
        this.roleId = roleId;
    }

    public boolean isUser() {
        return user;
    }

    public void setUser(boolean user) {
        this.user = user;
    }

    public boolean isTutor() {
        return tutor;
    }

    public void setTutor(boolean tutor) {
        this.tutor = tutor;
    }

    public boolean isAdmin() {
        return admin;
    }

    public void setAdmin(boolean admin) {
        this.admin = admin;
    }

    @Override
    public String toString() {
        return "Role{" +
                "roleId=" + roleId +
                ", user='" + user + ''' +
                ", tutor=" + tutor + ''' +
                ", admin=" + admin +
                '}';
    }
}

public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException {
        ...
        Set<GrantedAuthority> grantedAuthorities = new HashSet<>();
        ...
        return new org.springframework.security.core.userdetails.User(user.getLogin(), user.getPassword(), grantedAuthorities);
    }