how to map a composite key (ID + FK) in JPA - Hibernate? (with little plus)

They ask me to do this mapping with JPA (what is marked in red is for a plus question) :D :

So I did this:

CENTRAL MANAGEMENT

@Entity
@Table(name = "gerencia_central")
public class GerenciaCentral implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @Column(name = "id_gerencia_c")
    private int gerenciaCenId;

    @Column(name = "codigo_gerencia_c_propio")
    private String codigoPropio;

    @Column(name = "descripcion_gerencia_c")
    private String descripcion;

    @Column(name = "descripcion_corta_gerencia_c")
    private String descripcionCorta;

    @Column(name = "estado_gerencia_c")
    private String estado;

    @OneToMany(mappedBy = "gerenciaCen", cascade = { CascadeType.ALL }, fetch = FetchType.LAZY, orphanRemoval = true)
    private List<Gerencia> listaGerencia;

MANAGEMENT

@Entity
@Table(name = "gerencia")
public class Gerencia implements Serializable {

    private static final long serialVersionUID = 1L;

    @EmbeddedId
    private GerenciaPK pk;

    @ManyToOne
    @JoinColumn(name = "id_gerencia_c", referencedColumnName = "id_gerencia_c", nullable = false, insertable = false, updatable = false)
    private GerenciaCentral gerenciaCen;

    @Column(name = "codigo_gerencia_propio", length = 4)
    private String codigoPropio;

    @Column(name = "descripcion_gerencia", length = 80)
    private String descripcion;

    @Column(name = "descripcion_corta_gerencia", length = 40)
    private String descripcionCorta;

    @Column(name = "estado_gerencia", length = 1)
    private String estado;

    @OneToMany(mappedBy = "gerencia", cascade = { CascadeType.ALL }, fetch = FetchType.LAZY, orphanRemoval = true)
    private List<AreaFuncional> listaAreafunc;

And the MANAGEMENT key

@Embeddable
public class GerenciaPK implements Serializable {

    private static final long serialVersionUID = 1L;

    @Column(name = "id_gerencia_c")
    private int gerenciaCenId;

    @Column(name = "id_gerencia")
    private int gerenciaId;

Needless to say, everyone has their Get and Set and Equals and Hash Code. Although for the case I think none of that matters. Continuing...

When executing the project, it creates the tables but not the relationships.

Very well. It is possible that I did something wrong when generating the schema. That's why I also checked by other means.

And even generating the Script of the DB

CREATE TABLE `gerencia` (
 `id_gerencia_c` int(11) NOT NULL,
 `id_gerencia` int(11) NOT NULL,
 `codigo_gerencia_propio` varchar(4) DEFAULT NULL,
 `descripcion_gerencia` varchar(80) DEFAULT NULL,
 `descripcion_corta_gerencia` varchar(40) DEFAULT NULL,
 `estado_gerencia` varchar(1) DEFAULT NULL,
   PRIMARY KEY (`id_gerencia_c`,`id_gerencia`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8;

I would like to know what is wrong. I do not necessarily ask what I have done wrong but anything else that is wrong. Until what they gave me to do.

QUESTION PLUS In the first image you see that I highlight a box in red. There they tell me to be an integer but 4 digits. Since the first ID must be "0001" I changed the integer to a string. And the autoincrement is already on my own. But I would like to know if there is a way to indicate all this to Hibernate so that it saves a number with leading zeros. Thanks.