Optional: or, ifPresentOrElse and stream

Optional<String> primary = Optional.empty();
Optional<String> fallback = Optional.of("cache");

System.out.println("or        = " + primary.or(() -> fallback).orElse("none"));

primary.ifPresentOrElse(
        v -> System.out.println("present: " + v),
        () -> System.out.println("ifPresentOrElse: nothing there"));

System.out.println("filter    = " + Optional.of(4).filter(n -> n % 2 == 0).isPresent());
System.out.println("orElseGet = " + primary.orElseGet(() -> "computed lazily"));

or        = cache
ifPresentOrElse: nothing there
filter    = true
orElseGet = computed lazily