spring REST template to send fax with attachment

Hi,

Please find below the REST call to the "send fax" api.
Though the fax is being sent, the attachment is not sent.

Can you please help if the request is missing some entity?

byte[] attachment = getBVendorRenewalLetter();
MultiValueMap<String,Object> bodyMap = new LinkedMultiValueMap<String,Object>();
bodyMap.add("file", attachment);
bodyMap.add("to", "test phone number");
bodyMap.add("Authorization", accessToken);

HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);
headers.setContentDispositionFormData("content", "testFile.pdf");
headers.add("to", "test phone number");
headers.add("Authorization", accessToken);

HttpEntity<Object> requestEntity = new HttpEntity<Object>(bodyMap, headers);

ResponseEntity<RingCentralResponseDTO> response = restTemplate.exchange(" https://platform.devtest.ringcentral.com/restapi/v1.0/account/~/extension/~/fax";, HttpMethod.POST, requestEntity, RingCentralResponseDTO.class);

Thank You very much