Problem with 2 level inheritance class

[rv2931]

Hi
I have a doctrine database with 3 classes, MyChildChild inherits MyChild and MyChild inherits MyParent
My code is available here
Everything seems to be OK on doctrine side but with api-platform I have an error when trying any request

"@context": "/api/contexts/Error",
  "@type": "hydra:Error",
  "hydra:title": "An error occurred",
  "hydra:description": "Unable to generate an IRI for \"App\\Entity\\MyChildChild\"."

A soon as I remove the MyChildChild extends, then requests get OK

# MyChildChild.php
class MyChildChild extends MyChild
{...}

replaced by

# MyChildChild.php
class MyChildChild
{...}

Is there something to do in api-platform config when using complexe inheritance ?
or is it a bug ?
What's the meaning of the error ?
Thank you in advance
RV

<?php

namespace App\Entity;

use ApiPlatform\Core\Annotation\ApiResource;
use App\Repository\MyParentRepository;
use Doctrine\ORM\Mapping as ORM;
use App\Entity\MyChild;
use App\Entity\MyChildChild;

/**
 * @ApiResource()
 * @ORM\Entity(repositoryClass=MyParentRepository::class)
 * @ORM\InheritanceType("JOINED")
 * @ORM\DiscriminatorColumn(name="discr", type="string")
 * @ORM\DiscriminatorMap({"child"="MyChild","childchild"="MyChildChild"})
 */
class MyParent
{
    /**
     * @ORM\Id
     * @ORM\GeneratedValue
     * @ORM\Column(type="integer")
     */
    private $id;

    /**
     * @ORM\Column(type="string", length=255)
     */
    private $parentAttribute;

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

    public function getParentAttribute(): ?string
    {
        return $this->parentAttribute;
    }

    public function setParentAttribute(string $parentAttribute): self
    {
        $this->parentAttribute = $parentAttribute;

        return $this;
    }
}

<?php

namespace App\Entity;

use ApiPlatform\Core\Annotation\ApiResource;
use App\Repository\MyChildRepository;
use Doctrine\ORM\Mapping as ORM;
use App\Entity\MyParent;

/**
 * @ApiResource()
 * @ORM\Entity(repositoryClass=MyChildRepository::class)
 */
class MyChild extends MyParent
{
    /**
     * @ORM\Id
     * @ORM\GeneratedValue
     * @ORM\Column(type="integer")
     */
    private $id;

    /**
     * @ORM\Column(type="string", length=255)
     */
    private $childAttribute;

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

    public function getChildAttribute(): ?string
    {
        return $this->childAttribute;
    }

    public function setChildAttribute(string $childAttribute): self
    {
        $this->childAttribute = $childAttribute;

        return $this;
    }
}

<?php

namespace App\Entity;

use ApiPlatform\Core\Annotation\ApiResource;
use App\Repository\MyChildChildRepository;
use Doctrine\ORM\Mapping as ORM;
use App\Entity\MyChild;

/**
 * @ApiResource()
 * @ORM\Entity(repositoryClass=MyChildChildRepository::class)
 */
class MyChildChild extends MyChild
{
    /**
     * @ORM\Id
     * @ORM\GeneratedValue
     * @ORM\Column(type="integer")
     */
    private $id;

    /**
     * @ORM\Column(type="string", length=255)
     */
    private $MyChildChildAttribute;

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

    public function getMyChildChildAttribute(): ?string
    {
        return $this->MyChildChildAttribute;
    }

    public function setMyChildChildAttribute(string $MyChildChildAttribute): self
    {
        $this->MyChildChildAttribute = $MyChildChildAttribute;

        return $this;
    }
}

[rv2931]

Hi
I come back to my problem. It was finally due to a problem of discr column values in top parent table
In case of multiple inheritance, doctrine use only the top mot table to fill the discr column
So in this column, doctrine set/use the final class name, intermediate class names are not showing anywhere. As I adapting an existing database to be complient with doctrine inheritance way/structure, the problem was due to my adpatation script that was not filling the right classname
Sorry for that
RV