* there's no way to assign a {@code @Nullable T} to a field {@code T foo;} and instruct the
   * analysis that that means "plain {@code T}" rather than the inferred type {@code @Nullable T}.
   * (And even if annotations on local variables were permitted as an optional hint, no annotation
   * would be the right tool for the job here: {@code @Nullable} is the annotation that we're trying

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();

  /**
   * Returns the entry of the first element in this multiset, or {@code null} if this multiset is
   * empty.
   */
  @Nullable Entry<E> firstEntry();

  /**
   * Returns the entry of the last element in this multiset, or {@code null} if this multiset is
   * empty.
   */
  @Nullable Entry<E> lastEntry();

  /**
   * Returns and removes the entry associated with the lowest element in this multiset, or returns

  /**
   * Returns the entry of the first element in this multiset, or {@code null} if this multiset is
   * empty.
   */
  @Nullable Entry<E> firstEntry();

  /**
   * Returns the entry of the last element in this multiset, or {@code null} if this multiset is
   * empty.
   */
  @Nullable Entry<E> lastEntry();

  /**
   * Returns and removes the entry associated with the lowest element in this multiset, or returns

@GwtCompatible
@J2ktIncompatible
public final class EnumHashBiMap<K extends Enum<K>, V extends @Nullable Object>
    extends AbstractBiMap<K, V> {
  transient Class<K> keyTypeOrObjectUnderJ2cl;

  /**
   * Returns a new, empty {@code EnumHashBiMap} using the specified key type.
   *
   * @param keyType the key type
   */
  public static <K extends Enum<K>, V extends @Nullable Object> EnumHashBiMap<K, V> create(
      Class<K> keyType) {

   */
  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;
    }

     */
    public InvokerException(@Nullable String message) {
        super(message);
    }

    /**
     * Constructs a new {@code InvokerException} with the specified detail message and cause.
     *
     * @param message the detail message explaining the cause of the exception
     * @param cause the underlying cause of the exception
     */
    public InvokerException(@Nullable String message, @Nullable Throwable cause) {

   *
   * @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));

    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

          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;