"requestError": "RESOURCE_NAME_MISSING" in Google Ads api Upload UserData via REST INTERFACE

I am trying to upload user data using a google ads manager test account. The api I am trying to hit is 'https://googleads.googleapis.com/v10/customers/{customerId}:uploadUserData' . However upon sending request I am getting the following error.

"errors": [
                    {
                        "errorCodenter code heree": {
                            "requestError": "RESOURCE_NAME_MISSING"
                        },
                        "message": "Resource name is missing."
                    }
                ],

. Though I am giving all the credentials and my body is correct. Attached a postman screenshot below. enter image description here