private final boolean errors;

    private final T value;

    private final Iterable<? extends ModelProblem> problems;

    private Result(boolean errors, T model, Iterable<? extends ModelProblem> problems) {
        this.errors = errors;
        this.value = model;
        this.problems = problems;
    }

    public Iterable<? extends ModelProblem> getProblems() {
        return problems;
    }

  /** Returns an unmodifiable view of {@code iterable}. */
  public static <T extends @Nullable Object> Iterable<T> unmodifiableIterable(
      Iterable<? extends T> iterable) {
    checkNotNull(iterable);
    if (iterable instanceof UnmodifiableIterable || iterable instanceof ImmutableCollection) {
      @SuppressWarnings("unchecked") // Since it's unmodifiable, the covariant cast is safe
      Iterable<T> result = (Iterable<T>) iterable;

   * already a {@code FluentIterable}.
   *
   * <p><b>{@code Stream} equivalent:</b> {@link Collection#stream} if {@code iterable} is a {@link
   * Collection}; {@link Streams#stream(Iterable)} otherwise.
   */
  public static <E extends @Nullable Object> FluentIterable<E> from(Iterable<E> iterable) {
    return (iterable instanceof FluentIterable)
        ? (FluentIterable<E>) iterable

   * already a {@code FluentIterable}.
   *
   * <p><b>{@code Stream} equivalent:</b> {@link Collection#stream} if {@code iterable} is a {@link
   * Collection}; {@link Streams#stream(Iterable)} otherwise.
   */
  public static <E extends @Nullable Object> FluentIterable<E> from(Iterable<E> iterable) {
    return (iterable instanceof FluentIterable)
        ? (FluentIterable<E>) iterable

  public void testSize0() {
    Iterable<String> iterable = emptySet();
    assertEquals(0, Iterables.size(iterable));
  }

  public void testSize1Collection() {
    Iterable<String> iterable = singleton("a");
    assertEquals(1, Iterables.size(iterable));
  }

  public void testSize2NonCollection() {
    Iterable<Integer> iterable =
        new Iterable<Integer>() {
          @Override

   * @see #breadthFirst(Object)
   * @since 24.1
   */
  public final Iterable<N> breadthFirst(Iterable<? extends N> startNodes) {
    ImmutableSet<N> validated = validate(startNodes);
    return () -> newTraversal().breadthFirst(validated.iterator());
  }

  /**
   * Returns an unmodifiable {@code Iterable} over the nodes reachable from {@code startNode}, in

  public void testOf_empty() {
    Iterable<String> iterable = MinimalIterable.<String>of();
    Iterator<String> iterator = iterable.iterator();
    assertFalse(iterator.hasNext());
    assertThrows(NoSuchElementException.class, iterator::next);
    assertThrows(IllegalStateException.class, iterable::iterator);
  }

  public void testOf_one() {
    Iterable<String> iterable = MinimalIterable.of("a");

    @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());
  }

  @Override
  public <E extends Comparable<?>> E min(Iterator<E> iterator) {
    return NaturalOrdering.INSTANCE.max(iterator);
  }

  @Override
  public <E extends Comparable<?>> E min(Iterable<E> iterable) {
    return NaturalOrdering.INSTANCE.max(iterable);
  }

  @Override
  public <E extends Comparable<?>> E max(E a, E b) {
    return NaturalOrdering.INSTANCE.min(a, b);
  }

  @Override

    @SuppressWarnings("rawtypes") // the purpose is to test raw type
    Invokable<?, Iterable> delegate =
        Prepender.method("prepend", String.class, Iterable.class).returning(Iterable.class);
    assertEquals(new TypeToken<Iterable<String>>() {}, delegate.getReturnType());
    @SuppressWarnings("unchecked") // prepend() returns Iterable<String>
    Iterable<String> result = delegate.invoke(null, "a", ImmutableList.of("b", "c"));