protected function getGroupsForStep($step)
    {
        $groups = ['Default'];

        if ($step === static::CHECKOUT_STEP) {
            $groups[] = 'Checkout';
            $groups[] = 'Identity';
            $groups[] = 'Availability';
        } elseif ($step === static::SHIPMENT_STEP) {
            $groups[] = 'Availability';
        }

        return $groups;
    }