*/

  public static <V extends @Nullable Object> ListenableFuture<V> catching(
      ListenableFuture<? extends V> input,
      Class<Throwable> exceptionType,
      Function<? super Throwable, ? extends V> fallback,
      Executor executor) {
    return AbstractCatchingFuture.create(input, exceptionType, fallback, executor);
  }

  public static <V extends @Nullable Object> ListenableFuture<V> catchingAsync(

  }

  /**
   * Class for testing all permutations of nullable/non-nullable two-argument methods using
   * testMethod().
   *
   * <ul>
   *   <li>normalNormal: two params, neither is Nullable
   *   <li>nullableNormal: only first param is Nullable
   *   <li>normalNullable: only second param is Nullable
   *   <li>nullableNullable: both params are Nullable
   * </ul>
   */
  public static class TwoArg {

     */
    @Deprecated(since = "4.0.0", forRemoval = true)
    @Nullable
    static XmlNode merge(@Nullable XmlNode dominant, @Nullable XmlNode recessive) {
        return XmlService.merge(dominant, recessive, null);
    }

    @Nullable
    static XmlNode merge(
            @Nullable XmlNode dominant, @Nullable XmlNode recessive, @Nullable Boolean childMergeOverride) {

    super(cause);
  }

  public UncheckedTimeoutException(@Nullable String message, @Nullable Throwable cause) {
    super(message, cause);
  }

  private static final long serialVersionUID = 0;

import com.google.common.annotations.J2ktIncompatible;
import java.util.concurrent.Callable;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;
import org.jspecify.annotations.Nullable;

/**
 * An abstract {@code ScheduledExecutorService} that allows subclasses to {@linkplain
 * #wrapTask(Callable) wrap} tasks before they are submitted to the underlying executor.
 *

  @Override
  public @Nullable V remove(@Nullable Object key) {
    Map<K, V> delegate = delegateOrNull();
    if (delegate != null) {
      return delegate.remove(key);
    }
    Object oldValue = removeHelper(key);
    return (oldValue == NOT_FOUND) ? null : (V) oldValue;
  }

  private @Nullable Object removeHelper(@Nullable Object key) {
    if (needsAllocArrays()) {

    }
  }

  private static <V> ImmutableSet<V> valueSet(
      @Nullable Comparator<? super V> valueComparator, Collection<? extends V> values) {
    return (valueComparator == null)
        ? ImmutableSet.copyOf(values)
        : ImmutableSortedSet.copyOf(valueComparator, values);
  }

  private static <V> ImmutableSet<V> emptySet(@Nullable Comparator<? super V> valueComparator) {
    return (valueComparator == null)

  @VisibleForTesting
  static final class ValueEntry<K extends @Nullable Object, V extends @Nullable Object>
      extends SimpleImmutableEntry<K, V> {
    final int smearedValueHash;

    @Nullable ValueEntry<K, V> nextInValueBucket;

    private @Nullable ValueEntry<K, V> predecessorInValueSet;
    private @Nullable ValueEntry<K, V> successorInValueSet;

    private @Nullable ValueEntry<K, V> predecessorInMultimap;

@GwtIncompatible
public abstract class ForwardingNavigableMap<K extends @Nullable Object, V extends @Nullable Object>
    extends ForwardingSortedMap<K, V> implements NavigableMap<K, V> {

  /** Constructor for use by subclasses. */
  protected ForwardingNavigableMap() {}

  @Override
  protected abstract NavigableMap<K, V> delegate();

  @Override
  public @Nullable Entry<K, V> lowerEntry(@ParametricNullness K key) {

@GwtIncompatible
public abstract class ForwardingNavigableMap<K extends @Nullable Object, V extends @Nullable Object>
    extends ForwardingSortedMap<K, V> implements NavigableMap<K, V> {

  /** Constructor for use by subclasses. */
  protected ForwardingNavigableMap() {}

  @Override
  protected abstract NavigableMap<K, V> delegate();

  @Override
  public @Nullable Entry<K, V> lowerEntry(@ParametricNullness K key) {