code: @Override
    public void write(DataOutput out) throws IOException {
      super.write(out);
      out.writeInt(delHintsMap.length);
      for (long mapEntry : delHintsMap) {
        out.writeLong(mapEntry);
      }
      out.writeInt(delHints.length);
      for (String delHint : delHints) {
        Text.writeStringOpt(out, delHint);
      }
    }
docs: Writable