src/main/java/org/helm/notation2/parser/notation/HELM2Notation.java
@JsonIgnore
  public List<String> getGroupIDs() {
    List<String> listOfIDs = new ArrayList<String>();

    for (GroupingNotation grouping : listOfGroupings) {
      listOfIDs.add(grouping.getGroupID().getId());
    }
    return listOfIDs;
  }
@JsonIgnore
  public List<String> getGroupIDs() {
    List<String> listOfIDs = new ArrayList<String>();

    for (GroupingNotation grouping : listOfGroupings) {
      listOfIDs.add(grouping.getGroupID().getId());
    }
    return listOfIDs;
  }
method to get the ID's from all polymers

@return all ids from all polymers