Not able to add approvers using REST API in WorkFlow

Hi All,

I am doing a POC on creating a custom invoice approval flow using Oracle Integration Cloud. Now before creating the integration I was looking for an API that will add the approver to a workflow and I came across the below API endpoint.

/fscmRestApi/resources/11.13.18.05/workflowNotificationContents/action/addApprovers

When I tried to add approvers using this API it is giving me 400 Response.

Added the screenshot for reference.

And I am using this below Payload:

Action: POST

Request Header Media Type:

application/vnd.oracle.adf.action+json

{    "docHeaderId": 300000817037016,    "identificationKey": "TESTAPP_001",    "task": "FinApInvoiceApproval",    "taskNameSpace": "https://eklm-dev21.fa.us2.oraclecloud.com/apps/financials/payables/invoices/transactions/invoiceApprovalComposite",    "adhocApproverList": [        {            "newAssigneeUsername": "e335831",            "anchorUsername": "e226317",            "anchorSequenceNumber": 1        }    ]}