docs: public static Index<String> loadFromReader(BufferedReader br) throws IOException {
      HashIndex<String> index = new HashIndex<String>();
      String line = br.readLine();
      // terminate if EOF reached, or if a blank line is encountered.
      while ((line != null) && (line.length() > 0)) {
        int start = line.indexOf('=');
        if (start == -1 || start == line.length() - 1) {
          continue;
        }
        index.add(line.substring(start + 1));
        line = br.readLine();
      }
      return index;
    }