1. # comparator, nullsFirst，sorted
    2. fundImages.stream()
    3.     .map(this::toFundImageBO)
    4.     .sorted(Comparator.comparing(FundImageBO::getDisplayOrder, Comparator.nullsFirst(Integer::compareTo).reversed()))
    5.     .collect(Collectors.toList());
    7. # 收益率类型列表，降序排序类型集合多字段排序
    8. boList
    9. .stream()
    10. .map(this::convert2FundCollectInfo)
    11. .sorted(Comparator.comparing(FundCollectInfo::getMonthRate, Comparator.nullsFirst(BigDecimal::compareTo).reversed())
    12.       .thenComparing(FundCollectInfo::getOneYearRate, Comparator.nullsFirst(BigDecimal::compareTo)).reversed())