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

private String description;

public class UserExtra implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    private Long id;

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

    @OneToOne
    @MapsId
    private User user;
    ...

}

<input class="form-control" id="phone" ng-model="vm.registerAccount.phone" placeholder="global.form.phone.placeholder" />

public class ManagedUserVM extends UserDTO {

    // Default attributes omitted for brevity

    private String phone;

    ...

    public String getPhone() {
        return phone;
    }

}

public ResponseEntity<?> registerAccount(@Valid @RequestBody ManagedUserVM managedUserVM) {

    HttpHeaders textPlainHeaders = new HttpHeaders();
    textPlainHeaders.setContentType(MediaType.TEXT_PLAIN);

    return userRepository.findOneByLogin(managedUserVM.getLogin().toLowerCase())
        .map(user -> new ResponseEntity<>("login already in use", textPlainHeaders, HttpStatus.BAD_REQUEST))
        .orElseGet(() -> userRepository.findOneByEmail(managedUserVM.getEmail())
            .map(user -> new ResponseEntity<>("e-mail address already in use", textPlainHeaders, HttpStatus.BAD_REQUEST))
            .orElseGet(() -> {
                User user = userService
                    .createUser(managedUserVM.getLogin(), managedUserVM.getPassword(),
                        managedUserVM.getFirstName(), managedUserVM.getLastName(),
                        managedUserVM.getEmail().toLowerCase(), managedUserVM.getLangKey(),
                        managedUserVM.getPhone());

                mailService.sendActivationEmail(user);
                return new ResponseEntity<>(HttpStatus.CREATED);
            })
    );
}

@Inject
private UserExtraRepository userExtraRepository;

@Inject
private UserExtraSearchRepository userExtraSearchRepository;

...

public User createUser(String login, String password, String firstName, String lastName, String email,
                           String langKey, String phone) {

    User newUser = new User();
    Authority authority = authorityRepository.findOne(AuthoritiesConstants.USER);
    Set<Authority> authorities = new HashSet<>();
    String encryptedPassword = passwordEncoder.encode(password);
    newUser.setLogin(login);
    // new user gets initially a generated password
    newUser.setPassword(encryptedPassword);
    newUser.setFirstName(firstName);
    newUser.setLastName(lastName);
    newUser.setEmail(email);
    newUser.setLangKey(langKey);
    // new user is not active
    newUser.setActivated(false);
    // new user gets registration key
    newUser.setActivationKey(RandomUtil.generateActivationKey());
    authorities.add(authority);
    newUser.setAuthorities(authorities);
    userRepository.save(newUser);
    userSearchRepository.save(newUser);
    log.debug("Created Information for User: {}", newUser);

    // Create and save the UserExtra entity
    UserExtra newUserExtra = new UserExtra();
    newUserExtra.setUser(newUser);
    newUserExtra.setPhone(phone);
    userExtraRepository.save(newUserExtra);
    userExtraSearchRepository.save(newUserExtra);
    log.debug("Created Information for UserExtra: {}", newUserExtra);

    return newUser;
}