private static String requireProperty(HttpRequest request, String name) {
        return getProperty(request, name)
                .orElseThrow(() -> new IllegalArgumentException("Must specify '" + name + "' at '" + request.getUri().getRawPath() + "'"));
    }
Called at the end of response rendering, before generic status data is written. Called from a dedicated thread pool.
vespaclient-container-plugin/src/main/java/com/yahoo/document/restapi/resource/DocumentV1ApiHandler.java