Upon starting the payments which properties are required?
Are TraceId required for earlier initialized token payments after 2021.02.01?
TraceIds are not required for OneClick payments. For an interim perdio (until 2021.02.01) TraceIds will be required for all MerhcantInitiatedPayments and RecurringPayments.
We've received TraceId in the following format:
The TraceId is generated by the card issuer, and can be anything up to 100 characters. Whitespaces and 0s should also be left intact. You can read more about the TraceId here
Can we skip the additional data in subsequent payments that were required for 3DS authentication in the first Token Payment?
Additional data can't be ignored! The difference between the initial and subsequent token payment is that 3DS authentication is only required for the first, initial payment. More info can be found here
Do we have to generate the TraceId in the first Payment/Start, or is it generated by Barion?
TraceId is generated by the Card Issuer, so it is not required in the initial Payment/Start request. You have to store the TraceId, received in the GetPaymentState response, and send it in all subsequent payments. You can read more here. The exceptions are the subsequent payments of an already initialized token payments without 3DS. More info can be found here
When the amount of the first payment is different than the rest, I have to use MechantInitiatedPayment and not RecurringPayment. Right?
Yes, RecurringPayment can only be used, when the amounts of all the subsequent payments are the same or less. If only 1 is different (eg. you give discount/free for the first month), only MechantInitiatedPayment can be used. You can find more info here.