curl --request POST \
  --url https://api.buildwithchirp.com/v1/whatsapp/groups/{groupId}/join-requests/reject \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "joinRequestIds": [
    "join_req_123"
  ]
}
'

{
  "approved": [
    "<string>"
  ],
  "rejected": [
    "<string>"
  ],
  "failed": [
    {
      "id": "<string>",
      "error": "<string>"
    }
  ]
}