Spring Data - Relations with Atributes/Agregation

im new on spring data jpa and i had a problem. I dont know how to add an atribute between a entity and a relation.

1 Student have 1 course, 1 Course have 0:N Student

1 CustomChallenge have 1 Course, 1 Course have 0:N CustomChallege.

My doubt is how can i represent when a student from one course done a CustomChallenge? And how can i add an atributte? There is something else i should change or improve? Thanks for reading to everyon Model Diagram Class User

@Entity
@Inheritance(strategy = InheritanceType.JOINED)
public abstract class User {

    @Id
    @GeneratedValue (
        generator="system-uuid",
        strategy=GenerationType.SEQUENCE        
    )   
    @GenericGenerator(name="system-uuid", strategy = "uuid2")   
    private String id;  

    @NotBlank
    @Column(unique = true, length=10)
    private String ci;

Class Student

@Entity
@PrimaryKeyJoinColumn
public class Student extends User implements Cloneable{

    @ManyToOne
    @JsonManagedReference
    @NotNull
    private Course enrolledCourse;

Class Teacher

@Entity
@PrimaryKeyJoinColumn
public class Teacher extends User {

    @OneToMany(mappedBy = "teacher")
    @JsonProperty("coursesGiven")
    @JsonBackReference
    private List<Course> coursesGiven=new ArrayList<Course>();

Class CustomChallenge

@Entity
public class CustomChallenge{

    @Id 
    @GeneratedValue (
        generator="system-uuid",
        strategy=GenerationType.SEQUENCE        
    )   
    @GenericGenerator(name="system-uuid", strategy = "uuid2")
    private String id;
    @NotBlank
    @Column(length = 50)
    private String name; 

@Entity
@Table
public class Course {

    @Id @GeneratedValue
    private int id;
    
    @NotBlank
    @Column(length=64)
    @JsonProperty
    private String name;
    
    @ManyToOne
    @JsonManagedReference
    @JoinColumn
    private Teacher teacher;
    
    @OneToMany(mappedBy = "enrolledCourse")
    @JsonBackReference
    private List<Student> studentList=new ArrayList<Student>();