code: @Override
    public void writeTo(StreamOutput out) throws IOException {
      super.writeTo(out);
      request.writeTo(out);
  
      if (filteringAliases == null) {
        out.writeBoolean(false);
      } else {
        out.writeBoolean(true);
        out.writeStringArray(filteringAliases);
      }
    }
docs: Serialize
  
  @param out the output
  @throws IOException