docs: public static List<String> readLines(String filename) {
      List<String> lines = Lists.newArrayList();
      try {
        BufferedReader in = new BufferedReader(new FileReader(filename));
        String line;
        while ((line = in.readLine()) != null) {
          // Ignore blank lines.
          if (line.trim().length() > 0) {
            lines.add(line);
          }
        }
        in.close();
      } catch (IOException e) {
        throw new RuntimeException(e);
      }
      return lines;
    }