private static String metaToJson(Deployment deployment) {
        Slime slime = new Slime();
        Cursor rootObject = slime.setObject();
        deployment.version().ifPresent(version -> rootObject.setString("vespaVersion", version));
        if (deployment.isDryRun())
            rootObject.setString("dryRun", "true");
        return toJson(slime);
    }
Returns a JSON representation of the deployment metadata.
hosted-api/src/main/java/ai/vespa/hosted/api/ControllerHttpClient.java