docs: public static File toFile(final String filename) {
          if (filename == null) {
              return null;
          }
          String f;
          try {
              f = URLDecoder.decode(filename, UTF8);
          } catch (final UnsupportedEncodingException e) {
              throw new RuntimeException(e);
          }
          f = f.replace(WINDOWS_SEPARATOR, File.separator).replace(UNIX_SEPARATOR, File.separator);
          return new File(f);
      }