InvalidDefinitionException: No serializer found for class org.hibernate.proxy.pojo.javassist.JavassistLazyInitializer and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: com.sample.scrumboard.models.User_$$_jvsta02_1["handler"])

@RestController
@RequestMapping(path="/user")
@JsonIgnoreProperties(ignoreUnknown = true)
public class UserRestController {

    private UserRepository repository;

    @Autowired
    public UserRestController(UserRepository repository){
        this.repository = repository;
    }

    @GetMapping(value = "/list")
    public List<User> getUsers(){
        return repository.findAll();
    }

    @GetMapping(value = "/{id}")
    public @ResponseBody User getUserById(@PathVariable Long id, User user){
            user = repository.getOne(id);
            return user;
    }
}

@Entity
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "userId", nullable = false, updatable = false)
    private Long id;

    @NotNull
    @Size(min=2, max=20)
    private String firstName;

    @NotNull
    @Size(min=2, max=30)
    private String lastName;

    @NotNull
    @Size(min=2, max=20)
    private String userName;

    @NotNull
    @Size(min=2, max=30)
    private String passWord;

    @NotNull
    @Email
    private String email;

    //the mappedBy element must be used to specify the relationship field or property of the entity that is the owner of the relationship
    @OneToMany(mappedBy = "owner", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
    @JsonIgnore
    private List<UserStory> userStoryList;

    public User() {
    }

    public User(String firstName, String lastName, String userName, String passWord, String email) {
        this.firstName = firstName;
        this.lastName = lastName;
        this.userName = userName;
        this.passWord = passWord;
        this.email = email;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", firstName='" + firstName + ''' +
                ", lastName='" + lastName + ''' +
                ", userName='" + userName + ''' +
                ", passWord='" + passWord + ''' +
                ", email='" + email + ''' +
                '}';
    }

    public Long getId() {
        return id;
    }

    public void setId(Long id) {
        this.id = id;
    }

    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 getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getPassWord() {
        return passWord;
    }

    public void setPassWord(String passWord) {
        this.passWord = passWord;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public List<UserStory> getUserStoryList() {
        return userStoryList;
    }

    public void setUserStoryList(List<UserStory> userStoryList) {
        this.userStoryList = userStoryList;
    }
}