docs: private MarkdownDocStream pendingBreak() {
      if(newline == Newline.NONE) {
        return this;
      }
      out.append(newline == Newline.BREAK ? "\\\n" : newline == Newline.PAR ? "\n\n" : "\n");
      for(int i = indent, j = i; i > 0; i -= j) {
        out.append(WHITESPACES, 0, (j = i > WHITESPACES.length() ? WHITESPACES.length() : i));
      }
      newline = Newline.NONE;
      return this;
    }