code: protected void prepareForwardedRequestHeaders(RequestData request, ForwardDestination destination) {
          HttpHeaders headers = request.getHeaders();
          headers.set(HOST, destination.getUri().getAuthority());
          headers.remove(TE);
      }
docs: Remove any protocol-level headers from the clients request that
  do not apply to the new request we are sending to the remote server.
  
  @param request
  @param destination