code: private void copyResponseHeaders(HttpResponse proxyResponse, final HttpServletResponse servletResponse) {
          servletResponse.setCharacterEncoding(getContentCharSet(proxyResponse.getEntity()));
          from(Arrays.asList(proxyResponse.getAllHeaders())).filter(new Predicate<Header>() {
              @Override
              public boolean apply(Header header) {
                  return !hopByHopHeaders.containsHeader(header.getName());
              }
          }).transform(new Function<Header, Boolean>() {
              @Override
              public Boolean apply(Header header) {
                  servletResponse.addHeader(header.getName(), header.getValue());
                  return true;
              }
          }).toList();
      }
docs: Copy proxied response headers back to the servlet client.