docs: @SuppressWarnings({"MethodMayBeStatic"})
    protected void addAllInterningAndSuffixing(Collection<String> accumulator, Collection<String> addend, String suffix) {
      boolean nonNullSuffix = suffix != null && ! "".equals(suffix);
      if (nonNullSuffix) {
        suffix = '|' + suffix;
      }
      // boolean intern2 = flags.intern2;
      for (String feat : addend) {
        if (nonNullSuffix) {
          feat = feat.concat(suffix);
        }
        // if (intern2) {
        //   feat = feat.intern();
        // }
        accumulator.add(feat);
      }
    }