Hibernate object problem!

Good morning, everyone! I have a problem with the objects in Hibernate.

This is the method I use to extract the object:

public Moto loadMotoId(SessionFactory SessionBuilder, int idMoto) {
    Session conexion = SessionBuilder.openSession();

    Query q = conexion.createQuery("FROM Moto WHERE id = :_nid");
    q.setParameter("_nid", idMoto);

    List listMotos = q.list();

    Moto moto = new Moto();

    if (!listMotos.isEmpty()) {
        moto = (Moto) listMotos.get(0);
    } else {
        listMotos = null;
    }
    conexion.close();

    return moto;
}

This is part of the servlet code:

HttpSession session = request.getSession(true);
Operaciones objop = new Operaciones();    
Moto moto=objop.loadMotoId(SessionBuilder, idMoto);
session.setAttribute("moto", moto);

When I want to show the different attributes of the object in the jsp, the id fields related to other tables do not show them to me, for example:

I pick up the object previously saved in the servlet in the session variable:

<%
Moto moto = (Moto) session.getAttribute("moto");
%>

Part of the html code of a table where I want to show the type of motorbike of the motorbike object, which is a key to another table in my bbdd:

<td><%=moto.getTipoMoto().getNombre()%></td>

Well, in that line I get an error, the rest of the fields shows them correctly except for those that are foundational keys to other tables and I do not know why it is. Let's see if you can give me a cable. Thanks !!

I add the Moto class here:

package POJO;
// Generated 30-ene-2018 13:25:55 by Hibernate Tools 4.3.1


import java.util.HashSet;
import java.util.Set;

/**
 * Moto generated by hbm2java
 */
public class Moto  implements java.io.Serializable {


 private Integer id;
 private Diseno diseno;
 private TipoMoto tipoMoto;
 private String marca;
 private String modelo;
 private int cilindrada;
 private int caballos;
 private float aceleracion;
 private float consumo;
 private float velocidadMax;
 private float precioBase;
 private String imagen;
 private int stock;
 private Set reservas = new HashSet(0);

public Moto() {
}


public Moto(Diseno diseno, TipoMoto tipoMoto, String marca, String modelo, int cilindrada, int caballos, float aceleracion, float consumo, float velocidadMax, float precioBase, String imagen, int stock) {
    this.diseno = diseno;
    this.tipoMoto = tipoMoto;
    this.marca = marca;
    this.modelo = modelo;
    this.cilindrada = cilindrada;
    this.caballos = caballos;
    this.aceleracion = aceleracion;
    this.consumo = consumo;
    this.velocidadMax = velocidadMax;
    this.precioBase = precioBase;
    this.imagen = imagen;
    this.stock = stock;
}
public Moto(Diseno diseno, TipoMoto tipoMoto, String marca, String modelo, int cilindrada, int caballos, float aceleracion, float consumo, float velocidadMax, float precioBase, String imagen, int stock, Set reservas) {
   this.diseno = diseno;
   this.tipoMoto = tipoMoto;
   this.marca = marca;
   this.modelo = modelo;
   this.cilindrada = cilindrada;
   this.caballos = caballos;
   this.aceleracion = aceleracion;
   this.consumo = consumo;
   this.velocidadMax = velocidadMax;
   this.precioBase = precioBase;
   this.imagen = imagen;
   this.stock = stock;
   this.reservas = reservas;
}

public Integer getId() {
    return this.id;
}

public void setId(Integer id) {
    this.id = id;
}
public Diseno getDiseno() {
    return this.diseno;
}

public void setDiseno(Diseno diseno) {
    this.diseno = diseno;
}
public TipoMoto getTipoMoto() {
    return this.tipoMoto;
}

public void setTipoMoto(TipoMoto tipoMoto) {
    this.tipoMoto = tipoMoto;
}
public String getMarca() {
    return this.marca;
}

public void setMarca(String marca) {
    this.marca = marca;
}
public String getModelo() {
    return this.modelo;
}

public void setModelo(String modelo) {
    this.modelo = modelo;
}
public int getCilindrada() {
    return this.cilindrada;
}

public void setCilindrada(int cilindrada) {
    this.cilindrada = cilindrada;
}
public int getCaballos() {
    return this.caballos;
}

public void setCaballos(int caballos) {
    this.caballos = caballos;
}
public float getAceleracion() {
    return this.aceleracion;
}

public void setAceleracion(float aceleracion) {
    this.aceleracion = aceleracion;
}
public float getConsumo() {
    return this.consumo;
}

public void setConsumo(float consumo) {
    this.consumo = consumo;
}
public float getVelocidadMax() {
    return this.velocidadMax;
}

public void setVelocidadMax(float velocidadMax) {
    this.velocidadMax = velocidadMax;
}
public float getPrecioBase() {
    return this.precioBase;
}

public void setPrecioBase(float precioBase) {
    this.precioBase = precioBase;
}
public String getImagen() {
    return this.imagen;
}

public void setImagen(String imagen) {
    this.imagen = imagen;
}
public int getStock() {
    return this.stock;
}

public void setStock(int stock) {
    this.stock = stock;
}
public Set getReservas() {
    return this.reservas;
}

public void setReservas(Set reservas) {
    this.reservas = reservas;
}

}