code: List<MemberState> getActiveMemberStates(Comparator<MemberState> comparator) {
      List<MemberState> activeMembers = new ArrayList<>(getActiveMemberStates());
      Collections.sort(activeMembers, comparator);
      return activeMembers;
    }
docs: Returns a list of active members.
  
  @param comparator A comparator with which to sort the members list.
  @return The sorted members list.