@Override
      protected @Nullable Map<TodoIndexEntry, Integer> computeValue(@NotNull FileContent inputData,
                                                                    @NotNull DataIndexer<TodoIndexEntry, Integer, FileContent> indexer) {
        try {
          Map<TodoIndexEntry, Integer> result = indexer.map(inputData);
          return result.isEmpty() ? null : result;
        }
        catch (Exception e) {
          if (e instanceof ControlFlowException) throw e;
          throw new MapReduceIndexMappingException(e, indexer.getClass());
        }
      }
@Override
      protected @Nullable Map<TodoIndexEntry, Integer> computeValue(@NotNull FileContent inputData,
                                                                    @NotNull DataIndexer<TodoIndexEntry, Integer, FileContent> indexer)