My application running on google app engine, so can not use File. I want to save a pdf file on other site to google drive, but get a IllegalArgumentException

file.setMimeType("application/pdf");
mediaContent = new InputStreamContent(file.getMimeType(),
                   url.openStream());

try {
    File result = getDrive().files().insert(file, mediaContent)
                .execute();
        return result.getId();
    } catch (Exception e) {
        e.printStackTrace();
    }

Thanks