private static MultiPartStreamer toDataStream(Deployment deployment) {
        MultiPartStreamer streamer = new MultiPartStreamer();
        streamer.addJson("deployOptions", metaToJson(deployment));
        streamer.addFile("applicationZip", deployment.applicationZip());
        return streamer;
    }
Returns a multi part data stream with meta data and, if contained in the deployment, an application package.
hosted-api/src/main/java/ai/vespa/hosted/api/ControllerHttpClient.java