Flush new entity with relation when use relation in composite key throws ORMInvalidArgumentException

[don-tre]

/**
 * Class Entity
 *
 * @Entity(repositoryClass="TestRepo")
 * @Table(name="test_entity")
 */
class Entity
{
    /**
     * @var int
     * @Id
     * @Column(type="integer")
     * @GeneratedValue
     */
    protected $id;

    /**
     * @var string
     * @Column(type="string")
     */
    protected $label = '';

    /**
     * @var Collection|Friend[]
     * @OneToMany(targetEntity="Friend", mappedBy="entity", cascade={"all"}, orphanRemoval=true)
     */
    protected $friends;

    public function __construct()
    {
        $this->friends = new ArrayCollection();
    }

    public function addFriend(Friend $friend)
    {
        $friend->setEntity($this);
        $this->friends->add($friend);

        return $this;
    }

    public function setLabel(string $label)
    {
        $this->label = $label;

        return $this;
    }
}

/**
 * Class Entity
 * @Entity
 * @Table(name="test_entity_friend")
 */
class Friend
{
    /**
     * @var Entity
     * @id
     * @ManyToOne(targetEntity="Entity", inversedBy="friends")
     */
    protected $entity;

    /**
     * @var string
     * @id
     * @Column(type="string", length=400)
     */
    protected $name = '';

    /**
     * @return string
     */
    public function getName(): string
    {
        return $this->name;
    }

    /**
     * @param string $name
     * @return $this
     */
    public function setName(string $name)
    {
        $this->name = $name;

        return $this;
    }

    public function setEntity(Entity $entity)
    {
        $this->entity = $entity;

        return $this;
    }
}

Usage:

$entity = new Entity();
$entity->setLabel('labelll');

$friend = new Friend();
$friend->setName('name');
$entity->addFriend($friend);

$entityManager->persist($entity);
$entityManager->flush();

Throws ORM/ORMInvalidArgumentException.php:68 "The given entity of type '\TestDoctrine\Entity\Friend' (\TestDoctrine\Entity\Friend@00000000309854b5000000005dfe4c27) has no identity/no id values set. It cannot be added to the identity map".

Because $entity has null id.

Flush after creating new Entity() and before adding $friend to $entity resolve this problem, but it makes many duct tapes.

Doctrine 2.6. Prev version works fine.