docs: private void appendOptionGroup(StringBuffer buff, OptionGroup group)
      {
          if (!group.isRequired())
          {
              buff.append("[");
          }
  
          List<Option> optList = new ArrayList<Option>(group.getOptions());
          if (getOptionComparator() != null)
          {
              Collections.sort(optList, getOptionComparator());
          }
          // for each option in the OptionGroup
          for (Iterator<Option> it = optList.iterator(); it.hasNext();)
          {
              // whether the option is required or not is handled at group level
              appendOption(buff, it.next(), true);
  
              if (it.hasNext())
              {
                  buff.append(" | ");
              }
          }
  
          if (!group.isRequired())
          {
              buff.append("]");
          }
      }