@UnstableApi
    default <T> CompletableFuture<List<T>> collect(
            Function<? super BodyPart, CompletableFuture<? extends T>> function,
            SubscriptionOption... options) {
        return bodyParts().mapAsync(function).collect(options);
    }
Collects the elements published by this {@link Multipart}.
The returned {@link CompletableFuture} will be notified when the elements are fully consumed.

<p>Note that if this {@link Multipart} was subscribed by other {@link Subscriber} already,
the returned {@link CompletableFuture} will be completed with an {@link IllegalStateException}.

<p>Note that a {@link MimeParsingException} or another exception can be raised while collecting
so handle it properly.
core/src/main/java/com/linecorp/armeria/common/multipart/Multipart.java