@Entity
@Getter
@Builder
@ToString
@AllArgsConstructor
@NoArgsConstructor(access = AccessLevel.PROTECTED)
public class Category {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "category_id")
    private Long id;

    private String name;
    private Long depth;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "parent")
    private Category parent;

    @OneToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "store_id")
    private Store store;

    @OneToMany(mappedBy = "parent")
    private List<Category> children = new ArrayList<>();

    public void addChild(Category child) {
        children.add(child);
    }
}

无法调用“java.util.List.add（Object）”，因为“this.children”为空
当我尝试parentCategory.addChild(childCategory)时
我用一个空列表初始化了它，但是为什么会这样呢？
空列表是否为null？
我想知道初始化的正确方法。