* 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 java.util.Map;
import java.util.Set;
import org.jspecify.annotations.Nullable;

/**
 * Methods factored out so that they can be emulated differently in GWT.
 *
 * @author Hayward Chan
 */
@GwtCompatible
final class Platform {
  /** Returns the platform preferred implementation of a map based on a hash table. */
  static <K extends @Nullable Object, V extends @Nullable Object>
      Map<K, V> newHashMapWithExpectedSize(int expectedSize) {

import java.util.concurrent.ConcurrentHashMap;
import org.jspecify.annotations.Nullable;

/**
 * Methods factored out so that they can be emulated differently in GWT.
 *
 * @author Hayward Chan
 */
@GwtCompatible
final class Platform {

  /** Returns the platform preferred implementation of a map based on a hash table. */
  static <K extends @Nullable Object, V extends @Nullable Object>
      Map<K, V> newHashMapWithExpectedSize(int expectedSize) {

import com.google.common.annotations.GwtCompatible;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;
import java.util.Optional;
import java.util.stream.Collector;
import org.jspecify.annotations.Nullable;

/**
 * Provides static methods for working with {@link Comparator} instances. For many other helpful
 * comparator utilities, see either {@code Comparator} itself (for Java 8+), or {@code

  }

  private static <K extends @Nullable Object> @Nullable K keyOrNull(@Nullable Node<K, ?> node) {
    return node == null ? null : node.key;
  }

  private static <V extends @Nullable Object> @Nullable V valueOrNull(@Nullable Node<?, V> node) {
    return node == null ? null : node.value;
  }

  private static final class InverseSerializedForm<
          K extends @Nullable Object, V extends @Nullable Object>

   * 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) {