completePayout method
Implementation
@override
Future<void> completePayout(String payoutId, String transferReference) async {
final DVPayoutRecord? record = _payouts[payoutId];
if (record == null) return;
_payouts[payoutId] = DVPayoutRecord(
id: record.id,
accountId: record.accountId,
amount: record.amount,
at: record.at,
transferReference: transferReference,
);
}