this.forward = forward;
  }

  @Override
  public int count(@Nullable Object element) {
    return forward.count(element);
  }

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

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

  @Override
  public int size() {

   * @return the replacement string, or {@code null} if no escaping was needed
   */
  public static @Nullable String computeReplacement(UnicodeEscaper escaper, int cp) {
    return stringOrNull(escaper.escape(cp));
  }

  private static @Nullable String stringOrNull(char @Nullable [] in) {
    return (in == null) ? null : new String(in);
  }

  }

  @Override
  public @Nullable E lower(E element) {
    return forward.higher(element);
  }

  @Override
  public @Nullable E floor(E element) {
    return forward.ceiling(element);
  }

  @Override
  public @Nullable E ceiling(E element) {
    return forward.floor(element);
  }

  @Override
  public @Nullable E higher(E element) {
    return forward.lower(element);
  }

   *
   * @since 19.0
   */
  public static <K, V> RemovalNotification<K, V> create(
      @Nullable K key, @Nullable V value, RemovalCause cause) {
    return new RemovalNotification<>(key, value, cause);
  }

  private RemovalNotification(@Nullable K key, @Nullable V value, RemovalCause cause) {
    super(key, value);
    this.cause = checkNotNull(cause);
  }

   * equal to any other equality groups added to this tester.
   *
   * <p>The {@code @Nullable} annotations on the {@code equalityGroup} parameter imply that the
   * objects, and the array itself, can be null. That is for programmer convenience, when the
   * objects come from factory methods that are themselves {@code @Nullable}. In reality neither the
   * array nor its contents can be null, but it is not useful to force the use of {@code

import com.google.common.annotations.GwtCompatible;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import java.util.NoSuchElementException;
import org.jspecify.annotations.Nullable;

/**
 * This class provides a skeletal implementation of the {@code Iterator} interface, to make this
 * interface easier to implement for certain types of data sources.
 *

    }

    @Override
    public @Nullable Entry<K, V> firstEntry() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate().firstEntry();
    }

    @Override
    public @Nullable Entry<K, V> floorEntry(K key) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate().floorEntry(key);
    }

    @Override
    public @Nullable K floorKey(K key) {

import org.jspecify.annotations.Nullable;

/**
 * GWT emulation of {@code SortedMultiset}, with {@code elementSet} reduced to returning a {@code
 * SortedSet} for GWT compatibility.
 *
 * @author Louis Wasserman
 * @since 11.0
 */
public interface SortedMultiset<E extends @Nullable Object> extends Multiset<E>, SortedIterable<E> {
  Comparator<? super E> comparator();

  @Nullable Entry<E> firstEntry();

      List<@Nullable String> listWithNulls = asList("a", null, "b");
      assertThrows(NullPointerException.class, () -> builder.addAll((List<String>) listWithNulls));
    }

    {
      ImmutableList.Builder<String> builder = ImmutableList.builder();
      Iterator<@Nullable String> iteratorWithNulls =
          Arrays.<@Nullable String>asList("a", null, "b").iterator();
      assertThrows(

  // But before Java 9, our only way not to inherit ThreadLocals is to zap them after the thread
  // is created, by accessing a private field.
  private static final @Nullable Constructor<Thread> bigThreadConstructor =
      getBigThreadConstructor();

  private static final @Nullable Field inheritableThreadLocals =
      (bigThreadConstructor == null) ? getInheritableThreadLocalsField() : null;

  /** Constructs a new finalizer thread. */