@Override
    public String getAccumulatorUpdater(ChainVariable inVar, String map) {
      String key = myKeyExtractor.getText();
      String merger = myCollector.getMerger(inVar, map, key);
      if (merger != null) return merger;
      String acc = map + ".computeIfAbsent(" + key + "," + myKeyVar + "->" + myCollector.getSupplier() + ")";
      return myCollector.getAccumulatorUpdater(inVar, acc);
    }
@Override
    public String getAccumulatorUpdater(ChainVariable inVar, String map)