Salut j'ai une erreur je veux récupérer le cin de l'objet chefequipe merci

<?php
/**
 * Created by PhpStorm.
 * User: USER
 * Date: 18/02/2019
 * Time: 15:40
 */

namespace CredBundle\Entity;
use Doctrine\ORM\Mapping As ORM ;
use Symfony\Bridge\Doctrine\Validator\Constraints as DoctrineAssert;
use Symfony\Bridge\Doctrine\Validator\Constraints\UniqueEntity;
/**
 * class Employer
 * @package CredBundle\Entity
 */
/**
 * @ORM\Entity
 */
class Employer
{
    /**
     *
     *
     * @ORM\Column(type="integer",options={"auto_increment":false})
     * @ORM\Id
     *
     */
    public $cin;
    /**
     * @ORM\Column(type="string", length=255)
     */
    public $nom;
    /**
     * @ORM\Column(type="string", length=255)
     */
    public $prenom;
    /**
     * @ORM\Column(type="string", length=255)
     */
    public $fonction;
    /**
     * @ORM\Column(type="integer")
     */
    public $telephone;
    /**
     * @ORM\Column(type="integer")
     */
    public $age;
    /**
     * @ORM\Column(type="float")
     *
     */
    public $jourmaladie;
    /**
     * @ORM\Column(type="float")
     */

    public $jourconge;
    /**
     * @ORM\Column(type="float")
     */
    public $joursup;
    /**
     * @ORM\Column(type="string", length=255 , unique=true)
     */
   public $Email;
    /**
     * @ORM\Column(type="integer")
     */
    public $id_hierarchique;
    /**
     * @ORM\OneToMany(targetEntity="Conge", mappedBy="Employer")
     */
    public $id_conge ;
    /**
     *
     * @ORM\Column(type="string", length=255)
     */
    public $administration ;
    /**
     * @ORM\ManyToOne(targetEntity="chefequipe", inversedBy="Employer")
     * @ORM\JoinColumn(name="chefequipe", referencedColumnName="cin", onDelete="CASCADE")
     *
     */
    public $chefequipe;
    /**
     * @return mixed
     */
    public function getCin()
    {
        return $this->cin;
    }

    /**
     * @param mixed $cin
     */
    public function setCin($cin)
    {
        $this->cin = $cin;
    }

    /**
     * @return mixed
     */
    public function getNom()
    {
        return $this->nom;
    }

    /**
     * @param mixed $nom
     */
    public function setNom($nom)
    {
        $this->nom = $nom;
    }

    /**
     * @return mixed
     */
    public function getPrenom()
    {
        return $this->prenom;
    }

    /**
     * @param mixed $prenom
     */
    public function setPrenom($prenom)
    {
        $this->prenom = $prenom;
    }

    /**
     * @return mixed
     */
    public function getFonction()
    {
        return $this->fonction;
    }

    /**
     * @param mixed $fonction
     */
    public function setFonction($fonction)
    {
        $this->fonction = $fonction;
    }

    /**
     * @return mixed
     */
    public function getTelephone()
    {
        return $this->telephone;
    }

    /**
     * @param mixed $telephone
     */
    public function setTelephone($telephone)
    {
        $this->telephone = $telephone;
    }

    /**
     * @return mixed
     */
    public function getAge()
    {
        return $this->age;
    }

    /**
     * @param mixed $age
     */
    public function setAge($age)
    {
        $this->age = $age;
    }

    /**
     * @return mixed
     */
    public function getJourmaladie()
    {
        return $this->jourmaladie;
    }

    /**
     * @param mixed $jourmaladie
     */
    public function setJourmaladie($jourmaladie)
    {
        $this->jourmaladie = $jourmaladie;
    }

    /**
     * @return mixed
     */
    public function getJourconge()
    {
        return $this->jourconge;
    }

    /**
     * @param mixed $jourconge
     */
    public function setJourconge($jourconge)
    {
        $this->jourconge = $jourconge;
    }

    /**
     * @return mixed
     */
    public function getJoursup()
    {
        return $this->joursup;
    }

    /**
     * @param mixed $joursup
     */
    public function setJoursup($joursup)
    {
        $this->joursup = $joursup;
    }

    /**
     * @return mixed
     */
    public function getEmail()
    {
        return $this->Email;
    }

    /**
     * @param mixed $Email
     */
    public function setEmail($Email)
    {
        $this->Email = $Email;
    }

    /**
     * @return mixed
     */
    public function getIdHierarchique()
    {
        return $this->id_hierarchique;
    }

    /**
     * @param mixed $id_hierarchique
     */
    public function setIdHierarchique($id_hierarchique)
    {
        $this->id_hierarchique = $id_hierarchique;
    }

    /**
     * @return mixed
     */
    public function getIdConge()
    {
        return $this->id_conge;
    }

    /**
     * @param mixed $id_conge
     */
    public function setIdConge($id_conge)
    {
        $this->id_conge = $id_conge;
    }

    /**
     * @return mixed
     */
    public function getAdministration()
    {
        return $this->administration;
    }

    /**
     * @param mixed $administration
     */
    public function setAdministration($administration)
    {
        $this->administration = $administration;
    }

    /**
     * @return mixed
     */
    public function getChefequipe()
    {
        return $this->chefequipe;
    }

    /**
     * @param mixed $chefequipe
     */
    public function setChefequipe($chefequipe)
    {
        $this->chefequipe = $chefequipe;
    }
}