code: public static List<WriteFuture> broadcast(Object message, Iterator<IoSession> sessions) {
          List<WriteFuture> answer = new ArrayList<>();
          broadcast(message, sessions, answer);
          return answer;
      }
docs: Writes the specified {@code message} to the specified {@code sessions}.
  If the specified {@code message} is an {@link IoBuffer}, the buffer is
  automatically duplicated using {@link IoBuffer#duplicate()}.