code: @Nullable
    private String parseDriveRoot(String path) {
      Matcher drivePathMatcher = DRIVE_LETTER_ROOT.matcher(path);
      if (drivePathMatcher.find()) {
        return path.substring(drivePathMatcher.start(), drivePathMatcher.end());
      }
      return null;
    }
docs: Parses a normal drive-letter root, e.g. "C:\".