Is there a way or RestAPI to mass update or cancel New item requests in Bulk?

Summary:

We're trying to cancel NIR in bulk. It is not possible through UI, so we've used a Rest API:
REST API for Oracle Fusion Cloud SCM

In the above API, the structure is incorrect. Placement of { is incorrect. When we tried to modify the API as per our needs, it is still failing.
We are trying to call the changeStatus action on the newItemRequests REST resource (/fscmRestApi/resources/11.13.18.05/newItemRequests/action/changeStatus) to programmatically update NIR statuses. Every request we send returns error:
 
"The request content does not represent an action or it has an invalid structure."
 
Troubleshooting done so far: