You forgot the map operation (and I would also filter out nulls): (just to be pedantic) foo.stream() .filter(s -> s != null) .map(s -> s.descriptio

You forgot the map operation (and I would also filter out nulls): (just to be pedantic) foo.stream() .filter(s -> s != null) .map(s -> s.description()) .filter(s -> !s.isEmpty()) .collect(Collectors.joining("\n"));