code: public $.T2<String, String> commandLine(CommanderClassMetaInfo classMetaInfo, AppClassLoader classLoader) {
          boolean hasOptions = classMetaInfo.hasOption(classLoader);
          String firstArg = null;
          boolean hasMoreArgs = false;
          for (CommandParamMetaInfo param : params) {
              if (param.optionInfo() != null) {
                  hasOptions = true;
              } else {
                  if (firstArg == null) {
                      firstArg = param.name();
                  } else {
                      hasMoreArgs = true;
                  }
              }
          }
          for (FieldOptionAnnoInfo fieldOptionAnnoInfo : classMetaInfo.fieldOptionAnnoInfoList(classLoader)) {
              hasOptions = true;
              if (null == firstArg) {
                  firstArg = fieldOptionAnnoInfo.fieldName();
              } else {
                  hasMoreArgs = true;
              }
          }
  
          S.Buffer sb = S.buffer(commandName);
          if (hasOptions) {
              sb.append(" [options]");
          }
          if (null != firstArg) {
              sb.append(" ");
              sb.append("[").append(firstArg);
              if (hasMoreArgs) {
                  sb.append("...");
              }
              sb.append("]");
          }
          return $.T2(sb.toString(), helpMsg());
      }
docs: Returns {@link act.handler.CliHandler#commandLine()}
  @return the command line
  @see act.handler.CliHandler#commandLine()