docs: public static ImmutableList<Integer> toCodepoints(final String s) {
      final ImmutableList.Builder<Integer> ret = ImmutableList.builder();
      for (int offset = 0; offset < s.length();) {
        final int codePoint = s.codePointAt(offset);
        ret.add(codePoint);
        offset += Character.charCount(codePoint);
      }
      return ret.build();
    }