private static int getLineNumber(@NotNull String lineString) {
    // some quick checks to avoid costly exceptions
    if (lineString.isEmpty() || lineString.length() > 9 || !Character.isDigit(lineString.charAt(0))) {
      return -1;
    }

    try {
      return Integer.parseInt(lineString);
    }
    catch (NumberFormatException e) {
      return -1;
    }
  }
private static int getLineNumber(@NotNull String lineString)