REST API call and payload - Reassign a transaction in Oracle Cloud HCM

The below payload is not available in documentation.

Method : PUT

API : bpm/api/4.0/tasks/{task_number}

Payload :

{
  "identities":[
     {
        "id":"finuser2",
        "type":"user"
     }
  ],
  "action":{
     "id":"REASSIGN",
     "type":"system"    
  },
  "comment":{"commentStr":"Second comment","commentScope":"BPM"}
}