The CancelOrder method can be sent to void the authorization before
any payment on an order have been made (CaptureOrder or auto-settled
InitiatePayment). This is only supported for card payments,
and may not be supported by all banks.
CancelOrder retry support
The CancelOrder method supports retries. I.e. the request can be sent
multiple times with the same parameters without any side effects,
until a terminal response is received. This is useful if e.g. the
response from the bank is delayed, not received at all or pending,
but a terminal response is still required by the merchant.
In order to use the retry capability, the merchant defined
parameter must be included in the first and all subsequent retried
CancelOrder requests within the same scope. The RequestId must be unique per MerchantId.