code: public static List<MonomerNotation> getListOfMonomerNotation(List<PolymerNotation> polymers) {
      List<MonomerNotation> items = new ArrayList<MonomerNotation>();
      for (PolymerNotation polymer : polymers) {
        items.addAll(polymer.getListMonomers());
      }
  
      return items;
  
    }
docs: method to get all MonomerNotations for all given polymers
  
  @param polymers List of PolymerNotation
  @return List of MonomerNotation