### Question:
FluentIterable implements Iterable<E> { public boolean contains(final Object object) { return IterableUtils.contains(iterable, object); } FluentIterable(); private  FluentIterable(final Iterable<E> iterable); @SuppressWarnings("unchecked") static FluentIterable<T> empty(); static FluentIterable<T> of(final T singleton); static FluentIterable<T> of(final T... elements); static FluentIterable<T> of(final Iterable<T> iterable); FluentIterable<E> append(final E... elements); FluentIterable<E> append(final Iterable<? extends E> other); FluentIterable<E> collate(final Iterable<? extends E> other); FluentIterable<E> collate(final Iterable<? extends E> other,
                                     final Comparator<? super E> comparator); FluentIterable<E> eval(); FluentIterable<E> filter(final Predicate<? super E> predicate); FluentIterable<E> limit(final long maxSize); FluentIterable<E> loop(); FluentIterable<E> reverse(); FluentIterable<E> skip(final long elementsToSkip); FluentIterable<O> transform(final Transformer<? super E, ? extends O> transformer); FluentIterable<E> unique(); FluentIterable<E> unmodifiable(); FluentIterable<E> zip(final Iterable<? extends E> other); FluentIterable<E> zip(final Iterable<? extends E>... others); @Override Iterator<E> iterator(); Enumeration<E> asEnumeration(); boolean allMatch(final Predicate<? super E> predicate); boolean anyMatch(final Predicate<? super E> predicate); boolean isEmpty(); boolean contains(final Object object); void forEach(final Closure<? super E> closure); E get(final int position); int size(); void copyInto(final Collection<? super E> collection); E[] toArray(final Class<E> arrayClass); List<E> toList(); @Override String toString();  }### Answer:
@Test public void contains() { assertTrue(FluentIterable.of(iterableEven).contains(2)); assertFalse(FluentIterable.of(iterableEven).contains(1)); assertFalse(FluentIterable.of(iterableEven).contains(null)); assertTrue(FluentIterable.of(iterableEven).append((Integer) null).contains(null)); }