Lazy loading is not working in OnetoMany Jpa relations

Below are my entity classes Instructor and Courses having OnetoMany Relations, where all CRUD Operation is working but while fetching Instructor I don't want courses to be fetched. But when I execute GET instructor By Id, It also fetches courses in Postman. This should be avoided.

public class Instructor {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private Long id;
    private String firstName;
    private String lastName;
    private String email;

   @OneToMany(mappedBy = "instructor", cascade = {CascadeType.ALL})
   @JsonManagedReference
   private List < Course > courses;
}

public class Course {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String title;

    @ManyToOne(fetch =FetchType.LAZY)
    @JoinColumn(name = "instructor_id")
    @JsonBackReference
    private Instructor instructor;
 }