foreach ($Products as $Product) {
    // なぜかエラーになるので再取得 The discriminator column "discriminator_type" is missing for "Eccube\Entity\ClassCategory" using the DQL alias "cc2"
    $productClasses = $this->productClassRepository->findBy(['Product' => $Product]);    // ★追加
    /* @var $builder \Symfony\Component\Form\FormBuilderInterface */
    $builder = $this->formFactory->createNamedBuilder('', AddCartType::class, null, [
        'product' => $this->productRepository->findWithSortedClassCategories($Product->getId()),
    ]);
    $addCartForm = $builder->getForm();
    $forms[$Product->getId()] = $addCartForm->createView();
}