code: public void updateNodeChangedSize(String nodePath, long delta)
     {
        Long oldDelta = calculatedChangedNodesSize.get(nodePath);
        Long newDelta = delta + (oldDelta != null ? oldDelta : 0);
  
        calculatedChangedNodesSize.put(nodePath, newDelta);
     }
docs: Updates {@link #calculatedChangedNodesSize} for particular
  node path.