Сделать полиморфную связь для комментариев?

trait CommentTrait
{
    /**
     * @ORM\ManyToMany(targetEntity="App\Entity\Comment", cascade={"persist"})
     * @ORM\JoinTable(
     *      joinColumns={@ORM\JoinColumn(referencedColumnName="id")},
     *      inverseJoinColumns={@ORM\JoinColumn(referencedColumnName="id")}
     * )
     */
    private $comments;

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

    public function getComments()
    {
        return $this->comments;
    }

    public function addComment(Comment $comment)
    {
        $this->comments[] = $comment;
    }
}

/**
 * @ORM\Entity(repositoryClass="App\Repository\CommentRepository")
 * @ORM\HasLifecycleCallbacks()
 */
class Comment
{
    /**
     * @ORM\Id()
     * @ORM\GeneratedValue()
     * @ORM\Column(type="integer")
     */
    private $id;

    /**
     * @ORM\ManyToOne(targetEntity="App\Entity\User")
     */
    private $user;

    /**
     * @ORM\Column(type="text", nullable=true)
     */
    private $message;

    /**
     * @ORM\Column(type="datetime", nullable=true)
     */
    private $updated_at;

    /**
     * @ORM\Column(type="datetime", nullable=true)
     */
    private $created_at;

    public function getId(): ?int
    {
        return $this->id;
    }

    public function getUser(): ?User
    {
        return $this->user;
    }

    public function setUser(?User $user): self
    {
        $this->user = $user;

        return $this;
    }

    public function getMessage(): ?string
    {
        return $this->message;
    }

    public function setMessage(?string $message): self
    {
        $this->message = $message;

        return $this;
    }

    public function getUpdatedAt(): ?\DateTimeInterface
    {
        return $this->updated_at;
    }

    public function setUpdatedAt(?\DateTimeInterface $updated_at): self
    {
        $this->updated_at = $updated_at;

        return $this;
    }

    public function getCreatedAt(): ?\DateTimeInterface
    {
        return $this->created_at;
    }

    public function setCreatedAt(?\DateTimeInterface $created_at): self
    {
        $this->created_at = $created_at;

        return $this;
    }

    /**
     * @ORM\PrePersist
     */
    public function setCreatedAtValue()
    {
        $this->created_at = new \DateTime();
    }
}