docs: public List<OkCoinFutureKline> getFutureKline(
        CurrencyPair currencyPair,
        OkCoinKlineType type,
        FuturesContract contractType,
        Integer size,
        Long since)
        throws IOException {
      List<Object[]> list =
          okCoin.getFutureKline(
              "1",
              OkCoinAdapters.adaptSymbol(currencyPair),
              type.getType(),
              contractType.getName(),
              size,
              since);
      List<OkCoinFutureKline> klineList = new ArrayList<>();
      list.stream().forEach(kline -> klineList.add(new OkCoinFutureKline(kline)));
      return klineList;
    }