Nasty hack Hamcrest Stream matcher

gistfile1.java

public class StreamMatchers {
    public static class StreamContainingInAnyOrderMatcher<T> extends DelegatingStreamMatcher<T> {
        public StreamContainingInAnyOrderMatcher(T... items) {
            super(org.hamcrest.Matchers.arrayContainingInAnyOrder(items), "Stream of ");
        }
    }

    public static class EmptyStreamMatcher<T> extends DelegatingStreamMatcher<T> {
        public EmptyStreamMatcher() {
            super(Matchers.emptyArray(), "Stream like ");
        }
    }

    public static class DelegatingStreamMatcher<T> extends TypeSafeMatcher<Stream<? extends T>> {
        private final Matcher<T[]> delegate;
        private final String descriptionPrefix;
        private Optional<Object[]> itemsAsArray = Optional.empty();

        public DelegatingStreamMatcher(Matcher<T[]> delegate, String descriptionPrefix) {
            this.delegate = delegate;
            this.descriptionPrefix = descriptionPrefix;
        }

        @Override
        public void describeTo(Description description) {
            description.appendText(descriptionPrefix);
            delegate.describeTo(description);
        }

        @Override
        protected boolean matchesSafely(Stream<? extends T> item) {
            itemsAsArray = Optional.of(item.toArray());
            return delegate.matches(itemsAsArray.get());
        }

        @Override
        protected void describeMismatchSafely(Stream<? extends T> item, Description mismatchDescription) {
            delegate.describeMismatch(itemsAsArray.get(), mismatchDescription);
        }
    }
}