long numberOfWords =
        Stream.of("the", "", "fox", "jumps", "over", "the", "", "dog")  // (1)
            .filter(Predicate.not(String::isEmpty))                     // (2)
            .collect(Collectors.counting());                            // (3)


    This programming style is both expressive and efficient. 

Err... I assume the author here is aware that it is neither, but perhaps struggles for something else to say in motivating this API. It's certainly an amusing remark.

I'd prefer either an imperative,

    for(w <- words) if(!w.empty) count++

or, an ergonomic dsl,

    words.filter( w -> !w.empty ).count

The strange namespacing of functional primitives, glued into an api via 'gather', 'collect' etc. is neither expressive not efficient. Though I concede it may be a necessary route for a JEP