docs: public List<String> getMatchingOptions(String opt)
      {
          opt = Util.stripLeadingHyphens(opt);
          
          List<String> matchingOpts = new ArrayList<String>();
  
          // for a perfect match return the single option only
          if (longOpts.keySet().contains(opt))
          {
              return Collections.singletonList(opt);
          }
  
          for (String longOpt : longOpts.keySet())
          {
              if (longOpt.startsWith(opt))
              {
                  matchingOpts.add(longOpt);
              }
          }
          
          return matchingOpts;
      }