code: @Override
      public void removeListener(IChemObjectListener col) {
          if (chemObjectListeners == null) {
              return;
          }
  
          List<IChemObjectListener> listeners = lazyChemObjectListeners();
          if (listeners.contains(col)) {
              listeners.remove(col);
          }
      }
docs: Use this to remove a ChemObjectListener from the ListenerList of this
  IChemObject. It will then not be notified of change in this object anymore.
  
  @param  col  The ChemObjectListener to be removed
  @see         #addListener