I have two model classes in a Spring web application:

User.java:

@Data
@AllArgsConstructor
@NoArgsConstructor
@Entity
public class User implements Serializable {

    @Id
    private String username;

    private String password;

    private String email;
}

Client.java:

@Data
@AllArgsConstructor
@NoArgsConstructor
@Entity
@IdClass(User.class)
public class Client {

    @Id
    @OneToOne
    @JoinColumn(name = "username")
    private User user;

    private String firstName;

    private String lastName;

    private String phoneNumber;

    private String address;
}

And a repository ClientRepository:

@Repository
public interface ClientRepository extends JpaRepository<Client, User> {}

When I run the application I get the following error:

This class [class com.example.auction.models.Client] does not define an IdClass

What is the reason for that? I used the IdClass annotation in Client class.