How to create a Supplier from another Supplier and filter out some items?

Question

Suppose Supplier<Optional<Item>> is the source and Supplier<Item> is what we want: the same items without Optional.Empty cases.

Answer 1

Inspired by Boris and khelwood:

Supplier<Item> filtered = Stream.generate(optSupplier)
        .flatMap(Optional::stream)
        .iterator()::next;

If you're pre-Java 9, replace flatMap with .filter(Optional::isPresent).map(Optional::get).