*/
  public static <A extends @Nullable Object, B extends @Nullable Object, C extends @Nullable Object>
      Function<A, C> compose(Function<B, C> g, Function<A, ? extends B> f) {
    return new FunctionComposition<>(g, f);
  }

  private static final class FunctionComposition<
          A extends @Nullable Object, B extends @Nullable Object, C extends @Nullable Object>
      implements Function<A, C>, Serializable {

    // ordering.reverse() might be optimized, so let it do its thing
    return ordering.<T>reverse().<@NonNull S>nullsLast();
  }

  @SuppressWarnings("unchecked") // still need the right way to explain this
  @Override
  public <S extends @Nullable T> Ordering<@Nullable S> nullsFirst() {
    return (Ordering<@Nullable S>) this;
  }

  @Override

    // ordering.reverse() might be optimized, so let it do its thing
    return ordering.<T>reverse().<@NonNull S>nullsFirst();
  }

  @Override
  public <S extends @Nullable T> Ordering<@Nullable S> nullsFirst() {
    return ordering.<@NonNull S>nullsFirst();
  }

  @SuppressWarnings("unchecked") // still need the right way to explain this
  @Override

    // ordering.reverse() might be optimized, so let it do its thing
    return ordering.<T>reverse().<@NonNull S>nullsFirst();
  }

  @Override
  public <S extends @Nullable T> Ordering<@Nullable S> nullsFirst() {
    return ordering.<@NonNull S>nullsFirst();
  }

  @SuppressWarnings("unchecked") // still need the right way to explain this
  @Override

    }
  }

  private static <E extends @Nullable Object> E getElementOrThrow(@Nullable Entry<E> entry) {
    if (entry == null) {
      throw new NoSuchElementException();
    }
    return entry.getElement();
  }

  private static <E extends @Nullable Object> @Nullable E getElementOrNull(
      @Nullable Entry<E> entry) {
    return (entry == null) ? null : entry.getElement();
  }

   * would lead to at least slighly more work at startup time.
   */
  @LazyInit private transient @Nullable Ordering<@Nullable Comparable<?>> nullsFirst;
  @LazyInit private transient @Nullable Ordering<@Nullable Comparable<?>> nullsLast;

  @Override
  @SuppressWarnings("unchecked") // TODO(kevinb): the right way to explain this??

import org.jspecify.annotations.Nullable;

abstract class AbstractFutureState<V extends @Nullable Object> extends InternalFutureFailureAccess
    implements ListenableFuture<V> {
  final boolean casListeners(@Nullable Listener expect, Listener update) {
    if (listeners == expect) {
      listeners = update;
      return true;
    }
    return false;
  }

  final @Nullable Listener gasListeners(Listener update) {

   *
   * @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));

  static final class ListFuture<V extends @Nullable Object>
      extends CollectionFuture<V, List<@Nullable V>> {
    ListFuture(
        ImmutableCollection<? extends ListenableFuture<? extends V>> futures,
        boolean allMustSucceed) {
      super(futures, allMustSucceed);
      init();
    }

    @Override
    public List<@Nullable V> combine(List<@Nullable Present<V>> values) {

   */
  public static <T extends @Nullable Object> Predicate<T> notNull() {
    return ObjectPredicate.NOT_NULL.withNarrowedType();
  }

  /**
   * Returns a predicate that evaluates to {@code true} if the given predicate evaluates to {@code
   * false}.
   *
   * <p><b>Discouraged:</b> Prefer using {@code predicate.negate()}.
   */
  public static <T extends @Nullable Object> Predicate<T> not(Predicate<T> predicate) {