Error 400 : The request was rejected because no multipart boundary was found

Hi

Getting this error when trying to upload:

{
   type: "http.ClientResponse",
   code: 400,
   headers: {
      "Strict-Transport-Security": "max-age=31536000",
      "Content-Length": "179",
      Date: "Mon, 19 Oct 2020 10:23:04 GMT",
      "Content-Type": "application/json; charset=UTF-8",
      Via: "1.1 mono004"
   },
   body: "{"code":"bad_request","help_url":"http://developers.box.com/docs/#errors","status":400,"message":"the request was rejected because no multipart boundary was found","type":"error"}"
}


My request

{
  "method": "POST",
  "url": "https://upload.box.com/api/2.0/files/content",
  "headers": {
  "Content-Type": "multipart/form-data",
  "Authorization": "Bearer xxxxxxxxxxxxxxxxxxxxxxxxxx"
},
"body": {
  "attributes": {
    "content_created_at": "2020-10-19T10:31:25.248Z",
    "content_modified_at": "2020-10-19T10:31:25.248Z",
    "name": "testphoto 00361.jpg",
    "parent": {
      "id": "124596773392"
    }
  },
    "file": "TRIMMEDBASE64STRING"
  }
}

Not sure what to do here.