Although the answers are 100% correct, a small suggestion to improve null case handling of the list itself with Optional:
List<String> listOfStuffFiltered = Optional.ofNullable(listOfStuff)
.orElseGet(Collections::emptyList)
.stream()
.filter(Objects::nonNull)
.collect(Collectors.toList());
The part Optional.ofNullable(listOfStuff).orElseGet(Collections::emptyList) will allow you to handle nicely the case when listOfStuff is null and return an emptyList instead of failing with NullPointerException.