docs: public File getAndMakeDirectory(final String param) {
      final File f = get(param, new StringToFile(),
          new AlwaysValid<File>(), "existing or creatable directory");
  
      if (f.exists()) {
        if (f.isDirectory()) {
          return f.getAbsoluteFile();
        } else {
          throw new ParameterValidationException(fullString(param), f
              .getAbsolutePath().toString(),
              new ValidationException("Not an existing or creatable directory"));
        }
      } else {
        f.getAbsoluteFile().mkdirs();
        return f.getAbsoluteFile();
      }
    }