How to use Submit supplier spend-authorization request REST API

Hello All,

I'm trying to submit a promote to spend authorization request through OIC using the following API: /fscmRestApi/resources/11.13.18.05/suppliers/{SupplierId}/action/submitSpendAuthorizationRequest with the payload:
{
  "name": "submitSpendAuthorizationRequest",
  "parameters": [{
    "justification": "Request to promote supplier to spend authorized"
  }]
}
and the header contentType set to application/vnd.oracle.adf.action+json. However, I'm receiving the error: The request content does not represent an action or it has an invalid structure. 400 Bad Request. Am I missing something when calling the REST API?

Version : 26A

Thanks you in Advance!

Nirmal