MarketCouponExample couponExample = new MarketCouponExample; ListMarketCoupon coupons = couponMapperselectByExamplecouponExample; ListMapString Object couponList = new ArrayList;

The error you are encountering is likely due to an inconsistent data type between the couponList field in the IndexVo class and the actual type of couponList in your code.

To fix this issue, make sure that the couponList field in the IndexVo class is defined as List<Map<String, Object>>. Double-check the class definition to ensure that the field is defined correctly.

If the field is already defined correctly, then the error might be caused by a different issue. In that case, please provide more information about the specific error message or stack trace so that we can assist you further.