@NotNull
  @Override
  protected Pair<Substring, Integer> parseSectionHeader(int lineNum) {
    final Substring line = getLine(lineNum);
    final Matcher matcher = SECTION_HEADER.matcher(line);
    if (matcher.matches()) {
      final Substring title = line.getMatcherGroup(matcher, 1).trim();
      if (isValidSectionTitle(title.toString())) {
        return Pair.create(title, lineNum + 1);
      }
    }
    return Pair.create(null, lineNum);
  }
@NotNull
  @Override
  protected Pair<Substring, Integer> parseSectionHeader(int lineNum)