@SuppressWarnings("NullableOptional") // Null passthrough is reasonable for type conversions
  @IgnoreJRERequirement // Users will use this only if they're already using Optional.
  public static <T> @Nullable Optional<T> fromJavaUtil(
      java.util.@Nullable Optional<T> javaUtilOptional) {
    return (javaUtilOptional == null) ? null : fromNullable(javaUtilOptional.orElse(null));
  }

  /**

    }

    @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) {

    Callable<@Nullable Void> completeSuccessfullyRunnable =
        () -> {
          if (currentFuture.get().set("set")) {
            numSuccessfulSetCalls.incrementAndGet();
          }
          awaitUnchecked(barrier);
          return null;
        };
    Callable<@Nullable Void> completeExceptionallyRunnable =
        new Callable<@Nullable Void>() {

    Callable<@Nullable Void> completeSuccessfullyRunnable =
        () -> {
          if (currentFuture.get().set("set")) {
            numSuccessfulSetCalls.incrementAndGet();
          }
          awaitUnchecked(barrier);
          return null;
        };
    Callable<@Nullable Void> completeExceptionallyRunnable =
        new Callable<@Nullable Void>() {

    public Comparator<? super Cut<C>> comparator() {
      return Ordering.natural();
    }

    @Override
    public boolean containsKey(@Nullable Object key) {
      return get(key) != null;
    }

    @Override
    public @Nullable Range<C> get(@Nullable Object key) {
      if (key instanceof Cut) {
        try {
          @SuppressWarnings("unchecked") // we catch CCEs
          Cut<C> cut = (Cut<C>) key;

import org.apache.maven.api.annotations.Nonnull;
import org.apache.maven.api.annotations.Nullable;

/**
 * An XML writer request.
 *
 * @since 4.0.0
 * @param <T> the object type to read
 */
@Experimental
public interface XmlWriterRequest<T> {

    @Nullable
    Path getPath();

    @Nullable
    OutputStream getOutputStream();

    @Nullable
    Writer getWriter();

    @Nonnull
    T getContent();

   *
   * @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);
  }

@GwtIncompatible // not worth using in GWT for now
final class CompactLinkedHashMap<K extends @Nullable Object, V extends @Nullable Object>
    extends CompactHashMap<K, V> {
  // TODO(lowasser): implement removeEldestEntry so this can be used as a drop-in replacement

  /** Creates an empty {@code CompactLinkedHashMap} instance. */
  public static <K extends @Nullable Object, V extends @Nullable Object>
      CompactLinkedHashMap<K, V> create() {

  private static final @Nullable Object jla = getJla();

  /**
   * The "getStackTraceElementMethod" method, only available on some JDKs so we use reflection to
   * find it when available. When this is null, use the slow way.
   */
  @J2ktIncompatible @GwtIncompatible // java.lang.reflect
  private static final @Nullable Method getStackTraceElementMethod =

    return delegate().offerLast(e);
  }

  @Override
  public @Nullable E peekFirst() {
    return delegate().peekFirst();
  }

  @Override
  public @Nullable E peekLast() {
    return delegate().peekLast();
  }

  @CanIgnoreReturnValue // TODO(cpovirk): Consider removing this?
  @Override
  public @Nullable E pollFirst() {
    return delegate().pollFirst();
  }