hibernate and oracle sequence GenericGenerator creates gap
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I've mapped my class as follow (omitted other fields as only ID matters):

    @Entity
    @Table(name = "MODEL_GROUP")
    @Cache(usage = CacheConcurrencyStrategy.TRANSACTIONAL)
    public class SettlementModelGroup implements Serializable
    {


    @Id
    @GeneratedValue(generator = "MODEL_GROUP_SEQ", strategy = GenerationType.SEQUENCE)
    @GenericGenerator(name = "MODEL_GROUP_SEQ",
            strategy = "sequence",
            parameters = @Parameter(name = "sequence", value = "SEQ_MODEL_GROUP_MODEL_GROUP_ID"))
    @Column(name = "MODEL_GROUP_ID", nullable = false)
    private Integer modelId;
    }

when I'm saving new object:

    Integer modelGroupId = sessionFactory.getCurrentSession().save( modelGroup );
    System.out.println( modelGroupId );

ID is set as for example `23`, but when I look at the database it is actually `24`. This is leading to many problems, as I'm using this ID later on. Any idea why it is making this gap?