Java – Retrofit android @Multipart Remove default headers

Making a @Multipart request adds these default headers (Content-Transfer-Encoding, Content-Type) to each section, is there any way to remove them?

//REQUEST BODY
--25d35373-d2c3-46a3-969f-f5a1fd5f781a 
Content-Disposition: form-data; name="client_id"
Content-Transfer-Encoding: binary <-- remove this one
Content-Type: application/json; charset=UTF-8 <-- remove this one
Content-Length: 34
"40ccfee680a844780a41fbe23ea89934"
//

Note: I don’t have access to the server, so I can’t get the server to accept these headers.

You can build the multipart body yourself this way (kotlin code, but the same idea can be expressed in java):

val mpart = MultipartBody.Builder()
            .addFormDataPart("param", paramValue)
            .addPart(null, someRequestBody).build() // <-- (*) see explanation below

thus, service method should looks like this:
@POST("upload/endpoint")
fun upload(@Body parts: MultipartBody)

(*) – This is the addPart(headers: Headers, reqBody: RequestBody) method, which removes the addition of ContentLength:, when you pass null to headers arg