docs: public Options addOptionGroup(OptionGroup group)
      {
          if (group.isRequired())
          {
              requiredOpts.add(group);
          }
  
          for (Option option : group.getOptions())
          {
              // an Option cannot be required if it is in an
              // OptionGroup, either the group is required or
              // nothing is required
              option.setRequired(false);
              addOption(option);
  
              optionGroups.put(option.getKey(), group);
          }
  
          return this;
      }