*
 * @param <B> the common supertype that all values will share. When in doubt, just use {@link
 *     Object}, or use {@code @Nullable Object} to allow null values.
 * @since 2.0
 */
@DoNotMock("Use ImmutableClassToInstanceMap or MutableClassToInstanceMap")
@GwtCompatible
public interface ClassToInstanceMap<B extends @Nullable Object>
    extends Map<Class<? extends @NonNull B>, B> {
  /**

   */
  static <T extends @Nullable Object> T[] toArrayImpl(
      @Nullable Object[] src, int offset, int len, T[] dst) {
    checkPositionIndexes(offset, offset + len, src.length);
    if (dst.length < len) {
      dst = newArray(dst, len);
    } else if (dst.length > len) {
      @Nullable Object[] unsoundlyCovariantArray = dst;
      unsoundlyCovariantArray[len] = null;
    }

   *
   * @since 20.0 (varargs overload since 2.0)
   */
  @CanIgnoreReturnValue
  public static <T> T checkNotNull(
      @Nullable T reference,
      String errorMessageTemplate,
      @Nullable Object p1,
      @Nullable Object p2,
      @Nullable Object p3,
      @Nullable Object p4) {
    if (reference == null) {
      throw new NullPointerException(Platform.lenientFormat(errorMessageTemplate, p1, p2, p3, p4));

 * @author Louis Wasserman
 */
@GwtCompatible
abstract class AbstractMultiset<E extends @Nullable Object> extends AbstractCollection<E>
    implements Multiset<E> {
  // Query Operations

  @Override
  public boolean isEmpty() {
    return entrySet().isEmpty();
  }

  @Override
  public boolean contains(@Nullable Object element) {
    return count(element) > 0;
  }

  // Modification Operations

import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * Tests for {@link Functions}.
 *
 * @author Mike Bostock
 * @author Vlad Patryshev
 */
@GwtCompatible
@NullMarked
public class FunctionsTest extends TestCase {

  public void testIdentity_same() {
    Function<@Nullable String, @Nullable String> identity = Functions.identity();
    assertThat(identity.apply(null)).isNull();

import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**
 * A test utility that verifies that your methods and constructors throw {@link
 * NullPointerException} or {@link UnsupportedOperationException} whenever null is passed to a
 * parameter whose declaration or type isn't annotated with an annotation with the simple name
 * {@code Nullable}, {@code CheckForNull}, {@code NullableType}, or {@code NullableDecl}.
 *

          null, null, (Entry<Object, Object>[]) ImmutableMap.EMPTY_ENTRY_ARRAY, 0, 0);

  static final double MAX_LOAD_FACTOR = 1.2;

  private final transient @Nullable ImmutableMapEntry<K, V> @Nullable [] keyTable;
  private final transient @Nullable ImmutableMapEntry<K, V> @Nullable [] valueTable;
  @VisibleForTesting final transient Entry<K, V>[] entries;
  private final transient int mask;
  private final transient int hashCode;

    return forwardMultiset();
  }

  @Override
  public @Nullable Entry<E> firstEntry() {
    return forwardMultiset().lastEntry();
  }

  @Override
  public @Nullable Entry<E> lastEntry() {
    return forwardMultiset().firstEntry();
  }

  abstract Iterator<Entry<E>> entryIterator();

  @LazyInit private transient @Nullable Set<Entry<E>> entrySet;

  @Override

  }

  @Override
  @ParametricNullness
  public E get(int index) {
    return delegate().get(index);
  }

  @Override
  public int indexOf(@Nullable Object element) {
    return delegate().indexOf(element);
  }

  @Override
  public int lastIndexOf(@Nullable Object element) {
    return delegate().lastIndexOf(element);
  }

  @Override
  public ListIterator<E> listIterator() {

                mergeFunction),
        (s1, s2) -> s1.combine(s2, mergeFunction),
        state -> state.toTable());
  }

  static <
          T extends @Nullable Object,
          R extends @Nullable Object,
          C extends @Nullable Object,
          V,
          I extends Table<R, C, V>>
      Collector<T, ?, I> toTable(
          Function<? super T, ? extends R> rowFunction,