anchor.diff:      ChId :: gri:entity_id(),
       ParType :: gri:entity_type(),
       ParId :: gri:entity_id()
  -}.
  +} | {space_already_supported_with_imported_storage, SpaceId :: binary(), StorageId :: binary()}.
   
   -type op_worker() :: user_not_supported | auto_cleaning_disabled
   | file_popularity_disabled
  
positive.code:     };
  to_json(?ERROR_SPACE_ALREADY_SUPPORTED_WITH_IMPORTED_STORAGE(SpaceId, StorageId)) ->
      #{
          <<"id">> => <<"spaceAlreadySupportedByImportedStorage">>,
          <<"details">> => #{
              <<"spaceId">> => SpaceId,
              <<"storageId">> => StorageId
          },
          <<"description">> => ?FMT("Space ~p is already supported by imported storage ~p.", [SpaceId, StorageId])
      };
  
  %%--------------------------------------------------------------------
  
negative.code:     ChTypeAtom = gri:deserialize_type(ChType),
      ParTypeAtom = gri:deserialize_type(ParType),
      ?ERROR_RELATION_ALREADY_EXISTS(ChTypeAtom, ChId, ParTypeAtom, ParId);
  from_json(#{<<"id">> := <<"spaceAlreadySupportedWithImportedStorage">>, <<"details">> := #{
      <<"spaceId">> := SpaceId, <<"storageId">> := StorageId}
  }) ->
      ?ERROR_SPACE_ALREADY_SUPPORTED_WITH_IMPORTED_STORAGE(SpaceId, StorageId);
  