@SuppressWarnings("unchecked")
    @Override
    public void render(OutputStream stream, ContentChannel channel, 
                       CompletionHandler completionHandler) throws IOException {
        if (renderer instanceof AsynchronousRenderer) {
            AsynchronousRenderer asyncRenderer = (AsynchronousRenderer)renderer;
            asyncRenderer.setNetworkWiring(channel, completionHandler);
        }
        renderer.renderResponse(stream, processingResponse, execution, processingRequest);
        // the stream is closed in AsynchronousSectionedRenderer, after all data
        // has arrived
    }
True if the return status has been set explicitly and should not be further changed
container-core/src/main/java/com/yahoo/processing/handler/ProcessingResponse.java