https://github.com/magento/magento2/blob/2.0.0/lib/internal/Magento/Framework/App/Config.php#L32-L46
Should be:
@param null|string|int|ScopeInterface $scopeCode [optional]
because $scopeCode can be also int or \Magento\Framework\App\ScopeInterface:
See also:
\Magento\Framework\App\Config\ScopePool::_getScopeCode() method has a wrong PHPDoc type for the $scopeCode parameter\Magento\Payment\Model\Method\AbstractMethod::getConfigData() method has a wrong PHPDoc type for the $storeId parameter\Magento\Payment\Model\Method\AbstractMethod::isActive() method has a wrong PHPDoc type for the $storeId parameter\Magento\Payment\Model\MethodInterface::isActive() method has a wrong PHPDoc type for the $storeId parameter\Magento\Payment\Model\MethodInterface::getConfigData() method has a wrong PHPDoc type for the $storeId parameter