@Entity
@Table (name="tb_categorias")
public class Categoria extends Persistivel implements java.io.Serializable {
        
   
	private static final long serialVersionUID = 1L;

	@Column (name = "descricao")
	private String descricao;
	 
    @ManyToOne (fetch=FetchType.EAGER, cascade = CascadeType.PERSIST)
    @JoinColumn (name = "categoria_pai_id")
    private Categoria categoriaPai;
	 
    @OneToMany(cascade=CascadeType.ALL, fetch=FetchType.EAGER)
    @JoinTable (name = "tb_subcategorias")
    private Collection<Categoria> subCategorias;

...