anchor.diff:  %% @end
   %%--------------------------------------------------------------------
   -spec fetch_service_configuration(onezone | {oneprovider, Domain :: binary(), Hostname :: binary()}) ->
  -    {ok, PeerVersion :: binary(), CompatibleOpVersions :: [binary()]} |
  +    {ok, json_utils:json_term()} |
       {error, {bad_response, Code :: integer(), Body :: binary()}} |
       {error, term()}.
   fetch_service_configuration(onezone) ->
  
positive.code: 
  -spec to_string(od_provider:id()) -> string().
  to_string(ProviderId) ->
      {ok, Name} = provider_logic:get_name(ProviderId),
      str_utils:format("'~ts' (~s)", [Name, ProviderId]).
  
  
  %%--------------------------------------------------------------------
  
negative.code:             {error, _} = Error ->
                  Error
          end
      catch Type:Reason ->
          ?debug_stacktrace("Cannot verify nonce for provider ~ts - nonce was '~s' - ~p:~p", [
              to_string(ProviderId), Nonce, Type, Reason
          ]),
          ?ERROR_UNAUTHORIZED
      end.
  
  