// Ensures that reply field is non-null
 //
 private void build() throws IOException {
   Request.Action action = request.action();
   if ((action != Request.Action.GET) && (action != Request.Action.HEAD)) {
     reply = new Reply(Reply.Code.METHOD_NOT_ALLOWED, new StringContent(request.toString()));
   }
   reply = new Reply(Reply.Code.OK, new FileContent(request.uri()), action);
 }