protected function getPaymentMethodsFieldset(array $paymentMethods, $key, array $options)
    {
        $fieldset = array(
            'type' => 'fieldset',
            'legend' => $this->t("{$key}Fieldset"),
            'description' => $this->t("desc_{$key}Fieldset"),
            'fields' => array(),
        );

        $options[0] = $this->t('option_use_default');
        foreach ($paymentMethods as $paymentMethodId => $paymentMethodLabel) {
            $fieldset['fields']["{$key}[{$paymentMethodId}]"] = array(
                'type' => 'select',
                'label' => $paymentMethodLabel,
                'options' => $options,
            );
        }
        return $fieldset;
    }