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;
    }
  }

/**
 * Tests for {@code ImmutableCollection}.
 *
 * @author Louis Wasserman
 */
@NullUnmarked
public class ImmutableCollectionTest extends TestCase {
  public void testCapacityExpansion() {
    assertEquals(1, ImmutableCollection.Builder.expandedCapacity(0, 1));
    assertEquals(2, ImmutableCollection.Builder.expandedCapacity(0, 2));
    assertEquals(2, ImmutableCollection.Builder.expandedCapacity(1, 2));
    assertEquals(

  @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;

/**
 * Tests for {@code ImmutableCollection}.
 *
 * @author Louis Wasserman
 */
@NullUnmarked
public class ImmutableCollectionTest extends TestCase {
  public void testCapacityExpansion() {
    assertEquals(1, ImmutableCollection.Builder.expandedCapacity(0, 1));
    assertEquals(2, ImmutableCollection.Builder.expandedCapacity(0, 2));
    assertEquals(2, ImmutableCollection.Builder.expandedCapacity(1, 2));
    assertEquals(

class RegularImmutableAsList<E> extends ImmutableAsList<E> {
  private final ImmutableCollection<E> delegate;
  private final ImmutableList<? extends E> delegateList;

  RegularImmutableAsList(ImmutableCollection<E> delegate, ImmutableList<? extends E> delegateList) {
    this.delegate = delegate;
    this.delegateList = delegateList;
  }

  RegularImmutableAsList(ImmutableCollection<E> delegate, Object[] array) {
    this(delegate, asImmutableList(array));

import org.jspecify.annotations.Nullable;

/**
 * List returned by {@link ImmutableCollection#asList} that delegates {@code contains} checks to the
 * backing collection.
 *
 * @author Jared Levy
 * @author Louis Wasserman
 */
@GwtCompatible
@SuppressWarnings("serial")
abstract class ImmutableAsList<E> extends ImmutableList<E> {
  abstract ImmutableCollection<E> delegateCollection();

  @Override

  @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;

import static com.google.common.collect.Lists.newArrayListWithCapacity;
import static java.util.Collections.unmodifiableList;

import com.google.common.annotations.GwtCompatible;
import com.google.common.collect.ImmutableCollection;
import com.google.common.collect.Lists;
import com.google.errorprone.annotations.concurrent.LazyInit;
import com.google.j2objc.annotations.RetainedLocalRef;
import java.util.Collections;
import java.util.List;

class RegularImmutableAsList<E> extends ImmutableAsList<E> {
  private final ImmutableCollection<E> delegate;
  private final ImmutableList<? extends E> delegateList;

  RegularImmutableAsList(ImmutableCollection<E> delegate, ImmutableList<? extends E> delegateList) {
    this.delegate = delegate;
    this.delegateList = delegateList;
  }

  RegularImmutableAsList(ImmutableCollection<E> delegate, Object[] array) {
    this(delegate, asImmutableList(array));

    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();
    }