anchor.diff:  
   -export_type([auth/0, client/0, params/0, urn/0]).
   
  --define(OZ_ENDPOINT_CACHE, oz_endpoint_cache).
  -
   %%%===================================================================
   %%% API
   %%%===================================================================
  
positive.code: %%%===================================================================
  %%% Internal functions
  %%%===================================================================
  
  %%--------------------------------------------------------------------
  %% @private @doc Caches OZ CA certificates.
  %% @end
  %%--------------------------------------------------------------------
  -spec cache_oz_cacerts(CaCerts :: [binary()]) -> ok.
  cache_oz_cacerts(CaCerts) ->
      try
          ets:new(?OZ_ENDPOINT_CACHE, [set, public, named_table]),
          ets:insert(?OZ_ENDPOINT_CACHE, {cacerts, CaCerts})
      catch
          _:Reason ->
              ?warning("Cannot cache OZ CA certificates due to: ~p", [Reason])
      end,
      ok.
  
  %%--------------------------------------------------------------------
  %% @private @doc Returns properly formatted auth headers 
  
negative.code:     ]).
  
  %%--------------------------------------------------------------------
  %% @doc Returns cached OZ CA certificates or loads them from a directory given
  %% by a oz_plugin:get_cacerts_dir/0 callback and stores them in the cache.
  %% @end
  %%--------------------------------------------------------------------
  -spec get_oz_cacerts() -> CaCerts :: [binary()].
  get_oz_cacerts() ->
      case application:get_env(ctool, oz_cacerts) of
          {ok, CaCerts} -> CaCerts;
          undefined ->
              CaCertDir = oz_plugin:get_cacerts_dir(),
              case file_utils:read_files({dir, CaCertDir}) of
                  {ok, CaCerts} ->
                      application:set_env(ctool, oz_cacerts, CaCerts),
                      CaCerts;
                  {error, Reason} ->
                      ?error("Cannot load OZ CA certificates due to: ~p", [Reason]),
                      []
              end
      end.
  
  %%--------------------------------------------------------------------
  