@Embeddable
public class OrgaoPk implements Comparable, Serializable {

   private String competencia;
   private int codigo;
   
   public OrgaoPk() {}
   
   public OrgaoPk(String competencia, int codigo) {
      this.competencia = competencia;
      this.codigo = codigo;
   }

   @Column(name = "fk_competencia", nullable = false, length = 6)
   public String getCompetencia() {
      return competencia;
   }
   (...)
   @Column(name = "codigo", nullable = false)
   public int getCodigo() {
      return codigo;
   }
   (...)
}

@Entity
@Table(name = "tb_orgao")
public class Orgao implements Comparable, Serializable {

   private OrgaoPk pk;
   private Servidor titular;

   @Id(generate = GeneratorType.NONE)
   public OrgaoPk getPk() {
      return pk;
   }
   (...)
   @ManyToOne(fetch = FetchType.LAZY)
   @JoinColumns({
      @JoinColumn(name = "fk_competencia", referencedColumnName = "fk_competencia", insertable = false, updatable = false, nullable = false, primaryKey = true),
      @JoinColumn(name = "fk_servidor_titular", referencedColumnName = "matricula", insertable = false, updatable = false, nullable = false, primaryKey = true)
   })
   public Servidor getTitular() {
      return titular;
   }