code: protected void copyResponseHeaders(HttpResponse proxyResponse, HttpServletResponse servletResponse)
     {
        for (Header header : proxyResponse.getAllHeaders())
        {
           if (hopByHopHeaders.containsHeader(header.getName()))
              continue;
           servletResponse.addHeader(header.getName(), header.getValue());
        }
     }
docs: Copy proxied response headers back to the servlet client.