@SuppressWarnings("serial")
@Entity
public class GradeModel implements Serializable{

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    private String course;

    private String finalGrade;

    public GradeModel(){

    }

    public String getCourse() {
        return course;
    }

    public void setCourse(String course) {
        this.course = course;
    }

    public String getFinalGrade() {
        return finalGrade;
    }

    public void setFinalGrade(String finalGrade) {
        this.finalGrade = finalGrade;
    }

    public Long getId() {
        return id;
    }
}


================================


@SuppressWarnings("serial")
@Entity
public class StudentModel implements Serializable{
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Long id;

    private String firstName;

    private String lastName;

    private Integer age;

    private ArrayList<GradeModel> listOfGrades;

    public StudentModel(){

    }

    @OneToMany(cascade = CascadeType.ALL)
    public ArrayList<GradeModel> getListOfGrades() {
        return listOfGrades;
    }

    public void setListOfGrades(ArrayList<GradeModel> listOfGrades) {
        this.listOfGrades = listOfGrades;
    }

    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 Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public Long getId() {
        return id;
    }
}