@org.hibernate.annotations.CollectionOfElements
    @JoinTable(name = "T_OBJECTCONSTRAINT",
            joinColumns = @JoinColumn(name = "OBJECT_ID"))
    @org.hibernate.annotations.CollectionId(
            columns = {@Column(name = "OBJECT_ID"),
                       @Column(name = "CONSTRAIN_TYPE")},
            type = ?????,
            generator=?????
    )
    private Set<ObjConstrain> constraints;