@Entity
public class ShopUser {
    public enum Role{
        USER,
        ADMIN
    }

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;
    private String name;
    private Role role;

    @OneToOne
    private Credentials credentials;

    public Role getRole() {
        return role;
    }

    public void setRole(Role role) {
        this.role = role;
    }

    public long getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Credentials getCredentials() {
        return credentials;
    }

    public void setCredentials(Credentials credentials) {
        this.credentials = credentials;
    }
}



 @Entity
public class Credentials {
    @Id
    private String email;
    private String password;


    @OneToOne(mappedBy = "credentials")
    private ShopUser shopUser;

    public String getEmail() {
        return email;
    }

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

    public String getPassword() {
        return password;
    }

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

    public ShopUser getShopUser() {
        return shopUser;
    }

    public void setShopUser(ShopUser shopUser) {
        this.shopUser = shopUser;
    }
}


@Named("userBean")
@SessionScoped
public class UserBean implements Serializable {

    private String name;
    private String email;
    private String password;

    @EJB
    private UserManager userManager;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getEmail() {
        return email;
    }

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

    public String getPassword() {
        return password;
    }

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


    public void createUser(){

        userManager.createCredentials(email, password);
        userManager.createUser(name);

    }
}

@Stateless
@LocalBean
public class UserManager {

    @PersistenceContext(unitName = "examplePU")
    private EntityManager entityManager;

    public ShopUser createUser(String name){

        ShopUser shopUser = new ShopUser();
        shopUser.setName(name);
        shopUser.setRole(ShopUser.Role.USER);

        entityManager.persist(shopUser);

        return shopUser;
    }

    public Credentials createCredentials(String email, String password){
        Credentials credentials = new Credentials();
        credentials.setEmail(email);
        credentials.setPassword(password);

        entityManager.persist(credentials);
        return credentials;
    }

}

public void createUser(){
    Credentials credentials = userManager.createCredentials(email, password);
    ShopUser user = userManager.createUser(name);
    user.setCredencials(credentials);
}