anchor.diff:  maybe_serve_file(RestPrefix, Plugins, Req, Path) ->
       case doc_root(RestPrefix, Plugins) of
           DocRoot when is_list(DocRoot) ->
  -            menelaus_util:serve_file(Req,
  -                                     Path,
  -                                     DocRoot,
  -                                     [{"Cache-Control", "max-age=10"}]);
  +            serve_file(Req, Path, DocRoot);
  +        {multiple_roots, DocRoots} ->
  +            serve_file_multiple_roots(Req, Path, DocRoots);
           undefined ->
               menelaus_util:reply_not_found(Req)
       end.
  
positive.code: -record(plugin, { name            :: service_name(),
                    proxy_strategy  :: proxy_strategy(),
                    rest_api_prefix :: rest_api_prefix(),
                    doc_root        :: string()}).
  -type plugin()  :: #plugin{}.
  -type plugins() :: [plugin()].
  
  
negative.code:         false ->
              undefined
      end.
  
  serve_file_multiple_roots(Req, Path, [DocRoot]) ->
      serve_file(Req, Path, DocRoot);
  serve_file_multiple_roots(Req, Path, [DocRoot | DocRoots]) ->
      File = filename:join(DocRoot, Path),
      case filelib:is_regular(File) of
          true ->
              serve_file(Req, Path, DocRoot);
          false ->
              serve_file_multiple_roots(Req, Path, DocRoots)
      end.
  
  serve_file(Req, Path, DocRoot) ->
      menelaus_util:serve_file(Req,
                               Path,
                               DocRoot,
                               [{"Cache-Control", "max-age=10"}]).
  
  %%% =============================================================
  %%%
  