curl --request POST \
  --url https://sandbox.cashfree.com/api/v2/subscriptions/physical-mandate-file/upload \
  --header 'Content-Type: multipart/form-data' \
  --header 'x-client-id: <x-client-id>' \
  --header 'x-client-secret: <x-client-secret>' \
  --form file='@example-file'

{
  "status": 200,
  "message": "File Uploaded Successfully",
  "data": {
    "pNachFileId": "1475380791"
  }
}