public interface Resource {

    default Stream<Resource> streamChildren() {
        return listChildren().stream();
    }

    default Stream<Resource> findResources(Predicate<Resource> resourcePredicate) {
        return streamChildren().filter(resourcePredicate);
    }

    default Optional<Resource> findResource(Predicate<Resource> resourcePredicate) {
        return findResources(resourcePredicate).findFirst();
    }

    default Optional<Resource> findResource(String childResourceName) {
        return findResource(resource -> resource.getName().equals(childResourceName));
    }
....