Iterable<String> iterable = asList("a", "b");
    Iterator<String> cycle = Iterators.cycle(iterable);
    cycle.next();
    assertThrows(UnsupportedOperationException.class, () -> cycle.remove());
  }

  public void testCycleRemoveAfterHasNext() {
    Iterable<String> iterable = Lists.newArrayList("a");
    Iterator<String> cycle = Iterators.cycle(iterable);
    assertTrue(cycle.hasNext());

    @SuppressWarnings("rawtypes") // Iterable.class
    TypeToken<? extends Iterable> genericType = TypeToken.toGenericType(Iterable.class);
    assertEquals(Iterable.class, genericType.getRawType());
    assertEquals(
        Types.newParameterizedType(Iterable.class, Iterable.class.getTypeParameters()[0]),
        genericType.getType());
  }

   * Returns an iterator that cycles indefinitely over the elements of {@code iterable}.
   *
   * <p>The returned iterator supports {@code remove()} if the provided iterator does. After {@code
   * remove()} is called, subsequent cycles omit the removed element, which is no longer in {@code
   * iterable}. The iterator's {@code hasNext()} method returns {@code true} until {@code iterable}
   * is empty.
   *

   * accepts non-{@code Collection} iterables and empty iterables.
   */
  public static <E extends Enum<E>> EnumSet<E> newEnumSet(
      Iterable<E> iterable, Class<E> elementType) {
    EnumSet<E> set = EnumSet.noneOf(elementType);
    Iterables.addAll(set, iterable);
    return set;
  }

  // HashSet

  /**
   * Creates a <i>mutable</i>, initially empty {@code HashSet} instance.
   *

   * input futures, if all succeed.
   *
   * <p>The list of results is in the same order as the input list.
   *
   * <p>This differs from {@link #successfulAsList(Iterable)} in that it will return a failed future
   * if any of the items fails.
   *
   * <p>Canceling this future will attempt to cancel all the component futures, and if any of the

 *
 * <h4>Combining</h4>
 *
 * To derive a {@code ClosingFuture} from two or more input steps, pass the input steps to {@link
 * #whenAllComplete(Iterable)} or {@link #whenAllSucceed(Iterable)} or its overloads.
 *
 * <h3>Cancelling</h3>
 *
 * Any step in a pipeline can be {@linkplain #cancel(boolean) cancelled}, even after another step

        .inOrder();
  }

  public void testToMapWithNullKeys() {
    Iterable<@Nullable String> strings = asList("one", null, "three");
    assertThrows(
        NullPointerException.class,
        () -> Maps.toMap((Iterable<String>) strings, Functions.constant("foo")));
  }

  public void testToMapWithNullValues() {
    Iterable<String> strings = ImmutableList.of("one", "two", "three");

    public boolean putAll(@ParametricNullness K key, Iterable<? extends V> values) {
      throw new UnsupportedOperationException();
    }

    @Override
    public boolean putAll(Multimap<? extends K, ? extends V> multimap) {
      throw new UnsupportedOperationException();
    }

    @Override
    public Set<V> replaceValues(@ParametricNullness K key, Iterable<? extends V> values) {

          @Override
          public Object load(Object key) throws Exception {
            return new Object();
          }

          @Override
          public Map<Object, Object> loadAll(Iterable<?> keys) throws Exception {
            Map<Object, Object> result = new HashMap<>();
            for (Object key : keys) {
              Object value = new Object();
              result.put(key, value);

        .inOrder();
  }

  public void testToMapWithNullKeys() {
    Iterable<@Nullable String> strings = asList("one", null, "three");
    assertThrows(
        NullPointerException.class,
        () -> Maps.toMap((Iterable<String>) strings, Functions.constant("foo")));
  }

  public void testToMapWithNullValues() {
    Iterable<String> strings = ImmutableList.of("one", "two", "three");