docs: public static void parse(final List<Pair<String, String>> tags,
        final String tag) {
      if (tag == null || tag.isEmpty() || tag.length() < 2) {
        throw new IllegalArgumentException("Missing tag pair");
      }
      if (tag.charAt(0) == '=') {
        tags.add(new Pair<String, String>(null, tag.substring(1)));
        return;
      } else if (tag.charAt(tag.length() - 1) == '=') {
        tags.add(new Pair<String, String>(tag.substring(0, tag.length() - 1), null));
        return;
      }
      
      final String[] kv = splitString(tag, '=');
      if (kv.length != 2 || kv[0].length() <= 0 || kv[1].length() <= 0) {
        throw new IllegalArgumentException("invalid tag: " + tag);
      }
      tags.add(new Pair<String, String>(kv[0], kv[1]));
    }