Given pay demand data creates a relevant record and returns unique
pay demand identifier.

Payload provides both economic and descriptive parameters of the payment being requested, as well as (optionally) destination bank details.

Optionality is controlled by a flag UseDefaultBeneficiaryAccount within payload,
and consists of either

• Explicitly specifying beneficiary's bank account details (PayeeName as well as IBAN and/or BBAN) , or
• Setting the flag UseDefaultBeneficiaryAccount to true and then using previously specified default bank account details.

In the latter case, both PayeeName and BBAN/IBAN fields in payload must be left blank or ommitted.

NOTE: Assignment of default bank accounts is done interactively by the end-user either via separate
partner onboarding workflow for the user, or via a user dashboard.

This operation is idempotent, meaning that if multiple requests are submitted
with the same idempotency id, then results of the first successful request will be returned.