java8 collection filter

java 8 stream filter remove

private void cleanDeadData(List<BcpResend> list) {
        java.util.Set<String> grupingThanFilter =
                list.stream().collect(Collectors.collectingAndThen(Collectors.groupingBy(BcpResend::getCid, Collectors.counting()), map -> {
                    map.values().removeIf(l -> l < 50);
                    return map.keySet();
                }));
        grupingThanFilter.forEach(cid -> {
            repository.deleteByCid(cid);
        });
    }

private void cleanDeadData(List list) {
java.util.Set<Optional> grupingThanFilter =
list.stream()
.collect(Collectors.collectingAndThen(
Collectors.groupingBy((c -> Optional.ofNullable(c.getCid())), Collectors.counting())
, map -> {
map.values().removeIf(l -> l < 50);
return map.keySet();
}));
grupingThanFilter.stream()
.filter(Optional::isPresent)
.forEach(cid -> {
repository.deleteByCid(cid.get());
});
}