* undocumented and subject to change.
   *
   * <p>Note that if {@code list} is a {@code List<String>}, then {@code ImmutableList.copyOf(list)}
   * returns an {@code ImmutableList<String>} containing each of the strings in {@code list}, while
   * {@code ImmutableList.of(list)} returns an {@code ImmutableList<List<String>>} containing one
   * element (the given list itself).
   *

  @SuppressWarnings("unchecked")
  public static <E> ImmutableList<E> of() {
    return (ImmutableList<E>) RegularImmutableList.EMPTY;
  }

  public static <E> ImmutableList<E> of(E e1) {
    return new SingletonImmutableList<E>(checkNotNull(e1));
  }

  public static <E> ImmutableList<E> of(E e1, E e2) {
    return new RegularImmutableList<E>(ImmutableList.<E>nullCheckedList(e1, e2));
  }

    @Override
    protected List<String> create(String[] elements) {
      return ImmutableList.copyOf(elements);
    }
  }

  public static class BuilderAddListGenerator extends TestStringListGenerator {
    @Override
    protected List<String> create(String[] elements) {
      ImmutableList.Builder<String> builder = ImmutableList.<String>builder();
      for (String element : elements) {
        builder.add(element);
      }

  @Benchmark
  int builderAdd(int reps) {
    int size = this.size;
    int dummy = 0;
    for (int rep = 0; rep < reps; rep++) {
      ImmutableList.Builder<Object> builder = ImmutableList.builder();
      for (int i = 0; i < size; i++) {
        builder.add(OBJECT);
      }
      dummy += builder.build().size();
    }
    return dummy;
  }

  @Benchmark
  int preSizedBuilderAdd(int reps) {
    int size = this.size;

  }

  private transient @Nullable ImmutableList<E> asList;

  public ImmutableList<E> asList() {
    ImmutableList<E> list = asList;
    return (list == null) ? (asList = createAsList()) : list;
  }

  ImmutableList<E> createAsList() {
    switch (size()) {
      case 0:
        return ImmutableList.of();
      case 1:
        return ImmutableList.of(iterator().next());
      default:

   *
   * @throws NullPointerException if any element of {@code tasks} is null
   */
  private <T extends @Nullable Object> ImmutableList<Callable<T>> wrapTasks(
      Collection<? extends Callable<T>> tasks) {
    ImmutableList.Builder<Callable<T>> builder = ImmutableList.builder();
    for (Callable<T> task : tasks) {
      builder.add(wrapTask(task));
    }
    return builder.build();
  }

    @LazyInit private transient ImmutableList<E> asList;

    @Override
    public ImmutableList<E> asList() {
      ImmutableList<E> result = asList;
      if (result == null) {
        return asList = createAsList();
      } else {
        return result;
      }
    }

    @Override
    ImmutableList<E> createAsList() {

          .put(ListIterator.class, ImmutableList.of().listIterator())
          .put(Iterable.class, ImmutableSet.of())
          .put(Collection.class, ImmutableList.of())
          .put(ImmutableCollection.class, ImmutableList.of())
          .put(List.class, ImmutableList.of())
          .put(ImmutableList.class, ImmutableList.of())
          .put(Set.class, ImmutableSet.of())

import static com.google.common.testing.NullPointerTester.isNullable;

import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import com.google.common.collect.ImmutableList;
import com.google.common.reflect.AbstractInvocationHandler;
import com.google.common.reflect.Invokable;
import com.google.common.reflect.Parameter;
import com.google.common.reflect.TypeToken;
import java.io.Serializable;

  public void testPutAllNullForbidden() {
    assertThrows(NullPointerException.class, () -> multimap().putAll(null, singletonList(v3())));
  }

  @SuppressWarnings("EmptyList") // ImmutableList doesn't support nullable element types
  @MapFeature.Require(SUPPORTS_PUT)
  public void testPutAllEmptyCollectionOnAbsentKey() {
    assertFalse(multimap().putAll(k3(), Collections.<V>emptyList()));
    expectUnchanged();