code: @GwtIncompatible("Unnecessary")
    private static void maybeCreateDirsForPath(String pathPrefix) {
      if (!Strings.isNullOrEmpty(pathPrefix)) {
        String dirName =
            pathPrefix.charAt(pathPrefix.length() - 1) == File.separatorChar
                ? pathPrefix.substring(0, pathPrefix.length() - 1)
                : new File(pathPrefix).getParent();
        if (dirName != null) {
          new File(dirName).mkdirs();
        }
      }
    }
docs: Creates any directories necessary to write a file that will have a given path prefix.