setPurchase example

$reference = $current;
                $cheapest = $price;
            }
        }
        // @codeCoverageIgnoreEnd
        $object = new CheapestPrice();
        $object->setRuleId($cheapest['rule_id']);
        $object->setVariantId($cheapest['variant_id']);
        $object->setParentId($cheapest['parent_id']);
        $object->setHasRange($hasRange);
        $object->setPurchase($cheapest['purchase_unit'] ? (float) $cheapest['purchase_unit'] : null);
        $object->setReference($cheapest['reference_unit'] ? (float) $cheapest['reference_unit'] : null);
        $object->setUnitId($cheapest['unit_id'] ?? null);

        $prices = [];

        $blueprint = new Price('', 1, 1, true);

        foreach ($cheapest['price'] as $row) {
            $price = clone $blueprint;
            $price->setCurrencyId($row['currencyId']);
            $price->setGross((float) $row['gross']);