Doctrine inverse side's collection field is randomly filled

Question

I have the following two entities address and user . and in one of my controllers I have this function :

public function initAddressAction($idUser)
{
    $em = $this->getDoctrine()->getManager();
    $address = new Address();

    /** @var User $user*/
    $user= $em->getRepository('AppBundle:User' )->find($idUser);
    if ($user!== null) {
        $address->setUser($user); 
            dump($user); // #1
            $addresses = $user->getAddresses()->toArray();
            dump($user);die; // #2
            ...} 

My question is why the first dump prints the user object with an empty array in the addresses field :

#collection: Doctrine\Common\Collections\ArrayCollection {#9487 ▼

  -elements: []`

WHEREAS the second dump prints the user object with a non empty array collection in the addresses field (there is actually one address in this array):

#collection: Doctrine\Common\Collections\ArrayCollection {#9487 ▼

  -elements: array:1 [▼

    0 => App\Entity\address{#81625 ▼`

User :

/**
 * @ORM\OneToMany(targetEntity="App\Entity\Address", mappedBy="user")
 */
private $addresses;

/**
 * Set addresses
 *
 * @param Collection $addresses
 */
public function setAddresses($addresses)
{
    $this->addresses= $addresses;
}

/**
 * Get addresses
 *
 * @return \Doctrine\Common\Collections\Collection
 */
public function getAddresses()
{
    return $this->addresses;
}

/**
 * Add address
 *
 * @param Address $address
 * @return User
 */
public function addAddress(Address$address)
{
    if (!$this->addresses->contains($address)) {
        $this->addresses[] = $address;
    }

    return $this;
}

/**
 * Remove address
 *
 * @param Address $address
 */
public function removeAddress(Address $address)
{
    $this->addresses->removeElement($address);
}

Address :

/**
 * @ORM\ManyToOne(targetEntity="App\Entity\User", inversedBy="adresses")
 * @ORM\JoinColumn(name="id_user", referencedColumnName="id_user", nullable=false)
 */
private $user

/**
 * @return User
 */
public function getUser()
{
    return $this->user;
}

/**
 * @param User $user
 */
public function setUser($user)
{
    $this->user= $user;
}