i try to upload a gzipped file as multipart content like this

addHeader(HttpHeaders.ContentType, ContentType.MultiPart.FormData.withParameter("boundary", boundary).toString())
            setBody(boundary, listOf(
                    PartData.FileItem({ file.inputStream().asInput() }, {}, headersOf(
                            HttpHeaders.ContentDisposition,
                            ContentDisposition.File
                                    .withParameter(ContentDisposition.Parameters.Name, "file")
                                    .withParameter(ContentDisposition.Parameters.FileName, "file.txt")
                                    .toString()
                    ))
            ))

but when i get it on the server side like this

GZIPInputStream(part.streamProvider())

it complains "Not in GZIP format" .. when i try the same code with the file directly it works. any ideas?