我有这段代码，它获取“rate”的数据，如果这些参数中的任何一个没有足够的值，我必须将值从参数更改为字符串“all”，那么什么是de-best方法呢？我的实际代码是：

Map<String, List<Example>> exampleMap= cacheExampleData.getExample();
BigDecimal rate = exampleMap
    .get(RequestDto.getCustomer() == null ? "ALL" : RequestDto.getCustomerSubsegment())
    .stream().filter(x -> x.getSaleChannel().equalsIgnoreCase(RequestDto.getChannelId()))
    .filter(x -> x.getFlowName().equalsIgnoreCase(flowName))
    .filter(x -> x.getCustomerType().equalsIgnoreCase(RequestDto.getCustomerSegment()))
    .map(Example::getRate).findFirst().orElse(null);

if (rate == null && RequestDto.getCustomerSubsegment() != null) {
     rate = exampleMap
    .get(Constant.All)
    .stream().filter(x -> x.getSaleChannel().equalsIgnoreCase(RequestDto.getChannelId()))
    .filter(x -> x.getFlowName().equalsIgnoreCase(flowName))
    .filter(x -> x.getCustomerType().equalsIgnoreCase(RequestDto.getCustomerSegment()))
    .map(Example::getRate).findFirst().orElse(null);
 }

if (rate == null) {
     rate = exampleMap
    .get(Constant.All)
    .stream().filter(x -> x.getSaleChannel().equalsIgnoreCase(Constant.All)
    .filter(x -> x.getFlowName().equalsIgnoreCase(flowName))
    .filter(x -> x.getCustomerType().equalsIgnoreCase(RequestDto.getCustomerSegment()))
    .map(Example::getRate).findFirst().orElse(null);
 }

.
.
.
if (rate == null) {
     Do the same but with ALL in the first and second...X element
 }