Collection<?> collection = (Collection<?>) elements;
        ensureRoomFor(collection.size());
        if (collection instanceof ImmutableCollection) {
          ImmutableCollection<?> immutableCollection = (ImmutableCollection<?>) collection;
          size = immutableCollection.copyIntoArray(contents, size);
          return this;
        }
      }
      super.addAll(elements);
      return this;
    }
  }

  @Override
  public ImmutableCollection<Entry<K, V>> entries() {
    return (ImmutableCollection<Entry<K, V>>) super.entries();
  }

  @Override
  ImmutableCollection<Entry<K, V>> createEntries() {
    return new EntryCollection<>(this);
  }

  private static final class EntryCollection<K, V> extends ImmutableCollection<Entry<K, V>> {
    @Weak final ImmutableMultimap<K, V> multimap;

  @Override
  public ImmutableCollection<Entry<K, V>> entries() {
    return (ImmutableCollection<Entry<K, V>>) super.entries();
  }

  @Override
  ImmutableCollection<Entry<K, V>> createEntries() {
    return new EntryCollection<>(this);
  }

  private static final class EntryCollection<K, V> extends ImmutableCollection<Entry<K, V>> {
    @Weak final ImmutableMultimap<K, V> multimap;

   */
  @LazyInit
  private @Nullable ImmutableCollection<? extends ListenableFuture<? extends InputT>> futures;

  private final boolean allMustSucceed;
  private final boolean collectsValues;

  AggregateFuture(
      ImmutableCollection<? extends ListenableFuture<? extends InputT>> futures,
      boolean allMustSucceed,
      boolean collectsValues) {

    if (elements instanceof ImmutableCollection) {
      /*
       * TODO: When given an ImmutableList that's a sublist, copy the referenced
       * portion of the array into a new array to save space?
       */
      @SuppressWarnings("unchecked") // all supported methods are covariant
      ImmutableCollection<E> list = (ImmutableCollection<E>) elements;
      return list.asList();
    }

        Collection<?> collection = (Collection<?>) elements;
        ensureRoomFor(collection.size());
        if (collection instanceof ImmutableCollection) {
          ImmutableCollection<?> immutableCollection = (ImmutableCollection<?>) collection;
          size = immutableCollection.copyIntoArray(contents, size);
          return this;
        }
      }
      super.addAll(elements);
      return this;
    }

import com.google.common.collect.ClassToInstanceMap;
import com.google.common.collect.ImmutableBiMap;
import com.google.common.collect.ImmutableClassToInstanceMap;
import com.google.common.collect.ImmutableCollection;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableListMultimap;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableMultimap;

   */
  public static <E> ImmutableList<E> copyOf(Collection<? extends E> elements) {
    if (elements instanceof ImmutableCollection) {
      @SuppressWarnings("unchecked") // all supported methods are covariant
      ImmutableList<E> list = ((ImmutableCollection<E>) elements).asList();
      return list.isPartialView() ? asImmutableList(list.toArray()) : list;
    }
    return construct(elements.toArray());

  final UnmodifiableIterator<Cell<R, C, V>> cellIterator() {
    throw new AssertionError("should never be called");
  }

  @Override
  public ImmutableCollection<V> values() {
    return (ImmutableCollection<V>) super.values();
  }

  @Override
  abstract ImmutableCollection<V> createValues();

  @Override
  final Iterator<V> valuesIterator() {
    throw new AssertionError("should never be called");
  }

 * {@link ImmutableCollection}.
 *
 * @since 2.0
 */
@GwtCompatible
@SuppressWarnings("serial") // we're overriding default serialization
public abstract class ImmutableSet<E> extends ImmutableCollection<E> implements Set<E> {
  static final int SPLITERATOR_CHARACTERISTICS =
      ImmutableCollection.SPLITERATOR_CHARACTERISTICS | Spliterator.DISTINCT;

  /**