String (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); }