我有一个想法，在SQL数据库中用spring Boot 技术实现UUID作为主键。目前，我在如何实现一个用UUID作为主键的自定义固定字符串上遇到了一个难题。下面是一个示例：这是一个典型的UUID：

08d88683-20fc-4884-a523-8f39a06d037f

但我想我的UUID看起来像这样：

USER-08d88683-20fc-4884-a523-8f39a06d037f

我如何使用Sping Boot 和Hibernate来实现这一点呢？下面是我的用户模型：

@Data
@Entity
@Table( name = "users",
        uniqueConstraints = {
                @UniqueConstraint(columnNames = "username"),
                @UniqueConstraint(columnNames = "email")
        })
@NoArgsConstructor
public class User {
    @Id
    @GeneratedValue(generator = "uuid2")
    @GenericGenerator(name = "uuid2", strategy = "uuid2")
    @Column(name = "id", updatable = false, nullable = false, columnDefinition = "VARCHAR(36)")
    @Type(type = "uuid-char")
    private UUID id;

    @NotBlank
    @Size(max = 20)
    private String username;

    @NotBlank
    @Size(max = 50)
    @Email
    private String email;

    @NotBlank
    @Size(max = 120)
    private String password;

    @ManyToMany(fetch = FetchType.LAZY)
    @JoinTable( name = "user_roles",
            joinColumns = @JoinColumn(name = "user_id"),
            inverseJoinColumns = @JoinColumn(name = "role_id"))
    private Set<Role> roles = new HashSet<>();

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