* subject to change.
   *
   * @since 2.0
   */
  public ImmutableList<E> asList() {
    return isEmpty() ? ImmutableList.of() : ImmutableList.asImmutableList(toArray());
  }

  /**
   * Returns {@code true} if this immutable collection's implementation contains references to
   * user-created objects that aren't accessible via this collection's methods. This is generally

// TODO(user): Consider moving this to GraphsTest.
@RunWith(JUnit4.class)
@NullUnmarked
public class GraphPropertiesTest {
  ImmutableList<MutableGraph<Integer>> graphsToTest;
  Graph<Integer> directedGraph;
  Graph<Integer> undirectedGraph;

  ImmutableList<MutableNetwork<Integer, String>> networksToTest;
  Network<Integer, String> directedNetwork;
  Network<Integer, String> undirectedNetwork;

  @Before

 *       typically because the type forbids nullable type arguments: For example, {@code
 *       ImmutableList.get} returns {@code E}, but that value is never {@code null}. (Accordingly,
 *       {@code ImmutableList} is declared to forbid {@code ImmutableList<@Nullable String>}.)
 *   <li>methods whose return type is a type variable but which can return {@code null} regardless

 *       typically because the type forbids nullable type arguments: For example, {@code
 *       ImmutableList.get} returns {@code E}, but that value is never {@code null}. (Accordingly,
 *       {@code ImmutableList} is declared to forbid {@code ImmutableList<@Nullable String>}.)
 *   <li>methods whose return type is a type variable but which can return {@code null} regardless

 *       typically because the type forbids nullable type arguments: For example, {@code
 *       ImmutableList.get} returns {@code E}, but that value is never {@code null}. (Accordingly,
 *       {@code ImmutableList} is declared to forbid {@code ImmutableList<@Nullable String>}.)
 *   <li>methods whose return type is a type variable but which can return {@code null} regardless

 *       typically because the type forbids nullable type arguments: For example, {@code
 *       ImmutableList.get} returns {@code E}, but that value is never {@code null}. (Accordingly,
 *       {@code ImmutableList} is declared to forbid {@code ImmutableList<@Nullable String>}.)
 *   <li>methods whose return type is a type variable but which can return {@code null} regardless

 *       typically because the type forbids nullable type arguments: For example, {@code
 *       ImmutableList.get} returns {@code E}, but that value is never {@code null}. (Accordingly,
 *       {@code ImmutableList} is declared to forbid {@code ImmutableList<@Nullable String>}.)
 *   <li>methods whose return type is a type variable but which can return {@code null} regardless

 */

package com.google.common.io;

import static com.google.common.collect.ImmutableList.toImmutableList;
import static com.google.common.truth.Truth.assertThat;
import static java.nio.charset.StandardCharsets.UTF_8;

import com.google.common.base.Optional;
import com.google.common.collect.ImmutableList;
import com.google.common.io.SourceSinkFactory.ByteSourceFactory;

import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import com.google.common.collect.HashMultimap;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterators;
import com.google.common.collect.Lists;
import com.google.common.collect.Maps;
import com.google.common.collect.Multimap;

 * backing collection.
 *
 * @author Jared Levy
 * @author Louis Wasserman
 */
@GwtCompatible
@SuppressWarnings("serial")
abstract class ImmutableAsList<E> extends ImmutableList<E> {
  abstract ImmutableCollection<E> delegateCollection();

  @Override
  public boolean contains(@Nullable Object target) {
    // The collection's contains() is at least as fast as ImmutableList's