class TraceableHttpClientRequest implements HttpClientRequest {

    @Override
    public void addHeader(String header, String value) {
        Collection<String> existingValues = request.headers().get(header);
        if (existingValues == null) {
            existingValues = new ArrayList<>();
        }
        existingValues.add(value);
        request.headers().put(header, existingValues);
    }

    public  TraceableHttpClientRequest(Request request);

}