code: public OptionGroup addOption(Option option) {
          if (option == null) {
              throw new IllegalArgumentException("Option cannot be null");
          }
  
          String value = option.getValue();
  
          if (options.containsKey(value)) {
              throw new IllegalArgumentException("An option with value '" + value + "' already exists in this group");
          }
  
          options.put(value, option);
          return this;
      }
docs: Adds an option to the option group.
  
  @param option Option, with value not repeated in the group
  @return This group