Проблема со связью @OneToOne - Error accessing field

пытаюсь построить связь @OneToOne, получаю ошибку Error accessing field [private java.lang.Long Group$GroupId.chatId] by reflection for persistent property [Group$GroupId#chatId] : Event.EventId(chatId=1, groupId=1)

@Data
@Entity
@NoArgsConstructor
public class Group {

    @EmbeddedId
    private GroupId id;

    @OneToOne(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    @JoinColumns({
            @JoinColumn(name = "chat_id", referencedColumnName = "chat_id", insertable = false, updatable = false),
            @JoinColumn(name = "group_id", referencedColumnName = "group_id", insertable = false, updatable = false)
    })
    private Event event;


    @Data
    @Embeddable
    @NoArgsConstructor
    @AllArgsConstructor
    public static class GroupId implements Serializable {

        @Column(name = "chat_id")
        private Long chatId;

        @Column(name = "group_id")
        private Long groupId;
    }
}

@Data
@Entity
@NoArgsConstructor
public class Event {

    @EmbeddedId
    private EventId id;

    @OneToOne(mappedBy = "event", fetch = FetchType.LAZY)
    private Group group;

    @Data
    @Embeddable
    @AllArgsConstructor
    @NoArgsConstructor
    public static class EventId implements Serializable {

        @Column(name = "chat_id")
        private Long chatId;

        @Column(name = "group_id")
        private Long groupId;
    }
}

Прошу подсказать, в чём проблема