code: private static NanoResponse maybeServeSpecial(RequestUri uri) {
      assert uri != null;
  
      if (uri.isHeadMethod()) {
        // Blank response used by R's uri.exists("/")
        if (uri.getUrl().equals("/"))
          return new NanoResponse(HTTP_OK, MIME_PLAINTEXT, "");
      }
      if (uri.isGetMethod()) {
        // url "/3/Foo/bar" => path ["", "GET", "Foo", "bar", "3"]
        String[] path = uri.getPath();
        if (path[2].equals("")) return redirectToFlow();
        if (path[2].equals("Logs") && path[3].equals("download")) return downloadLogs();
        if (path[2].equals("NodePersistentStorage.bin") && path.length == 6) return downloadNps(path[3], path[4]);
      }
      return null;
    }
docs: Handle any URLs that bypass the standard route approach.  This is stuff that has abnormal non-JSON response
  payloads.
  @param uri RequestUri object of the incoming request.
  @return Response object, or null if the request does not require any special handling.