-spec start_download(pid(), map(), map(), map(), map()) ->
                        {ok, adk_artifact_stream:stream(), map()} | {error, term()}.

-spec start_link() -> supervisor:startlink_ret().

-spec start_upload(pid(),
                   {module(), term()},
                   adk_artifact_service:scope(),
                   binary(),
                   map(),
                   map(),
                   map()) ->
                      {ok, adk_artifact_stream:stream(), map()} | {error, term()}.