Java 스트림에서 객체 목록을 선택 사항으로 효율적으로 변환하는 방법은 무엇입니까?

<code class="java">Optional<Other> result = things.stream()
    .map(this::resolve)
    .<Other>mapMulti(Optional::ifPresent)
    .findFirst();</code>

<code class="java">Optional<Other> result = things.stream()
    .map(this::resolve)
    .flatMap(Optional::stream)
    .findFirst();</code>

<code class="java">Optional<Other> result = things.stream()
    .map(this::resolve)
    .flatMap(o -> o.isPresent() ? Stream.of(o.get()) : Stream.empty())
    .findFirst();</code>

<code class="java">static <T> Stream<T> streamopt(Optional<T> opt) {
    if (opt.isPresent())
        return Stream.of(opt.get());
    else
        return Stream.empty();
}

Optional<Other> result = things.stream()
    .flatMap(t -> streamopt(resolve(t)))
    .findFirst();</code>