docs: private static int futuresLeverageOfConfig(ExchangeSpecification exchangeSpecification) {
  
      if (exchangeSpecification.getExchangeSpecificParameters().containsKey("Futures_Leverage")) {
        return Integer.valueOf(
            (String) exchangeSpecification.getExchangeSpecificParameters().get("Futures_Leverage"));
      } else {
        // default choice of 10x leverage is "safe" choice and default by OkCoin.
        return 10;
      }
    }