...
"billingOverride": [
{
"fixedAmount": "feeFixedAmount",
"id": "objectId",
"percentageAmount": "feePercentageAmount",
"sourceId": "feeSourceIdentifier",
"sourceType": "BillingAccountId",
"targetId": "feeTargetIdentifier",
"targetType": "BillingAccountId",
"reverse": "true",
"billingAmount": "billingAmountValue"
}
],
...