code: public final static void combineHELM2notation(HELM2Notation helm2notation, HELM2Notation newHELM2Notation) throws NotationException {
      HELM2NotationUtils.helm2notation = helm2notation;
      Map<String, String> mapIds = generateMapChangeIds(newHELM2Notation.getPolymerAndGroupingIDs());
      /* method to merge the new HELM2Notation into the existing one */
      /* section 1 */
      /* id's have to changed */
      section1(newHELM2Notation.getListOfPolymers(), mapIds);
      /* section 2 */
      section2(newHELM2Notation.getListOfConnections(), mapIds);
      /* section 3 */
      section3(newHELM2Notation.getListOfGroupings(), mapIds);
      /* section 4 */
      section4(newHELM2Notation.getListOfAnnotations(), mapIds);
    }
docs: method to add a new HELMNotation to another HELM2Notation, the new
  HELM2Notation will be merged to the first HELM2Notation
  
  @param helm2notation HELM2Notation
  @param newHELM2Notation new HELMNotation
  @throws NotationException if the HELMNotation is not valid