I am creating a flight booking application using spring boot. It has two entities: User and Flight

User entity:

@Entity
@Table(name = "User", uniqueConstraints = @UniqueConstraint(columnNames = "username"))
@Getter
@Setter
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    
    @Column
    private String username;
    
    @Column
    private String email;
    
    @Column
    private String password;    

    public User() {
        super();
    }

    public User(Long id, String username, String email, String password) {
        super();
        this.id = id;
        this.username = username;
        this.email = email;
        this.password = password;
    }
    
}

Flight entity:

@Entity
@Table(name = "Flight" , uniqueConstraints = @UniqueConstraint(columnNames = "flightNumber"))
@Getter
@Setter
public class Flight {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long flightId;
    
    @Column
    private String flightNumber;
    
    @Column
    private String airlineName;
    
    @Column
    private String flightType;
    
    @Column
    private String origin;
    
    @Column
    private String destination;
    
    @Column
    private LocalTime departure;
    
    @Column
    private LocalTime arrival;
    
    @Column
    private Date date;
    
    @Column
    private Integer AvailableSeats;
    
    @Column
    private String price;

    public Flight() {
        super();
    }


    public Flight(Long flightId, String flightNumber, String airlineName, String flightType, String origin, String destination, LocalTime departure, LocalTime arrival, Date date, Integer availableSeats, String price) {
        super();
        this.flightId = flightId;
        this.flightNumber = flightNumber;
        this.airlineName = airlineName;
        this.flightType = flightType;
        this.origin = origin;
        this.destination = destination;
        this.departure = departure;
        this.arrival = arrival;
        this.date = date;
        AvailableSeats = availableSeats;
        this.price = price;
    }

}

I want to create another entity called ‘Booking’ to store the booking records of users. It will have two columns, username (from User table) and flightNumber (from Flight table).
From what I understood, I have to do many-to-many mapping of User and Flight. How to achieve this in spring boot?