additionalData object is a generic container that can hold extra request fields. You may require to pass these fields along with payment modification data, for example, to better manage risky transactions or to initiate a payment using some local payment methods.
This functionality requires additional configuration on Adyen's end. To enable it, contact the Support Team.
Depending on your requirements, you can pass the following values as
additionalData in a modification request:
Mastercard UK Installments
This is the installment option selected by the shopper. It is required only if specified by the user.