"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