动态更改Fieldset Fields的必需参数

我有一个moneyFieldset有2个字段,金额和货币.

class MoneyFieldset ...
{
public function __construct($name = null, $options = array())
    {
        parent::__construct($name, $options);
        $this->setHydrator(...);

        $this->add(array(
            'name'    => 'currency',
            'type'    => 'select',
            'options' => array(
                'value_options' => \Core\Service\Money::getAvailableCurrencies(true),
            ),
            'attributes' => array(
                'value' => \Core\Service\Money::DEFAULT_CURRENCY,
            ),
        ));

        $this->add(array(
            'name'       => 'amount',
            'type'       => 'text',
        ));
    }
}
public function getInputFilterSpecification()
    {
        $default = [
            'amount' => [
                'required'    => false,
                'allow_empty' => true,
                'filters'     => [
                    ['name' => AmountFilter::class]
                ],
                'validators' => [
                ]
            ],
            'currency' => [
                'required'    => false,
                'allow_empty' => true,
                'filters'     => [
                    ['name' => StringToUpper::class]
                ],
                'validators' => [
                ]
            ]
        ];
        return \Zend\Stdlib\ArrayUtils::merge($default, $this->filterSpec, true);
    }

我在我的其他字段集中使用moneyFieldset:

        // Price Field
        $this->add(array(
            'name'       => 'price',
            'type'       => 'form.fieldset.moneyFieldset',
            'attributes' => array(
                'required'    => true,
                'invalidText' => 'Please type an amount'
            ),
            'options' => array(
                ...
            ),
        ));

当我像这样设置过滤器时:

    function getInputFilterSpecification()
    {
        'price' => [
            'required'    => true,
            'allow_empty' => false,
        ],
     }

它不起作用,因为价格有2个字段,那么我怎么能说价格[金额]和价格[curreny]是必需的？