LineItem.java

package org.books.domain;

import javax.persistence.*;

@Entity
public class LineItem {

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

    @ManyToOne
    private Book book;
    private int quantity;

    public void setBook(Book book) {
        this.book = book;
    }

    public Book getBook() {
        return book;
    }

    public void setQuantity(int quantity) {
        this.quantity = quantity;
    }

    public int getQuantity() {
        return quantity;
    }
}