getVariantDetailsForPremiumProducts example

if (empty($premium['available'])) {
                $premium['sDifference'] = $this->productModule->sFormatPrice(
                    $premium['startprice'] - $sBasketAmount
                );
            }
            $premium['sArticle'] = $this->productModule->sGetPromotionById(
                'fix',
                0,
                $premium['articleID']
            );
            $premium['startprice'] = $this->productModule->sFormatPrice($premium['startprice']);
            $premium['sVariants'] = $this->getVariantDetailsForPremiumProducts(
                (int) $premium['articleID'],
                (int) $premium['main_detail_id']
            );
        }

        return $premiums;
    }

    /** * @param int|null $categoryId * * @return array<array<string, mixed>> */