return new Present<>(
        checkNotNull(
            function.apply(reference),
            "the Function passed to Optional.transform() must not return null."));
  }

  @Override
  public boolean equals(@Nullable Object obj) {
    if (obj instanceof Present) {
      Present<?> other = (Present<?>) obj;
      return reference.equals(other.reference);
    }

 * SMB3 directory leasing is available and enabled.
 */
public class SmbFileDirectoryLeasingExtension {

    /**
     * Private constructor to prevent instantiation of this utility class
     */
    private SmbFileDirectoryLeasingExtension() {
        // Utility class - prevent instantiation
    }

    private static final Logger log = LoggerFactory.getLogger(SmbFileDirectoryLeasingExtension.class);

    /**

   * Invoked to request the service to stop.
   *
   * <p>By default this method does nothing.
   *
   * <p>Currently, this method is invoked while holding a lock. If an implementation of this method
   * blocks, it can prevent this service from changing state. If you need to performing a blocking
   * operation in order to trigger shutdown, consider instead registering a listener and

   * Invoked to request the service to stop.
   *
   * <p>By default this method does nothing.
   *
   * <p>Currently, this method is invoked while holding a lock. If an implementation of this method
   * blocks, it can prevent this service from changing state. If you need to performing a blocking
   * operation in order to trigger shutdown, consider instead registering a listener and

   * for an RPC may wait for a similar call that requests a long timeout, or a call by an
   * unprivileged user may return a resource accessible only to a privileged user making a similar
   * call. To prevent this problem, create a key object that includes all values that affect the
   * result of the query. Or use {@code LoadingCache.get(K)}, which lacks the ability to refer to
   * state other than that in the key.
   *

     *
     * @param o
     *            object to be removed from this set, if present.
     * @return true if the set contained the specified element.
     */
    @Override
    public boolean remove(final Object o) {
        return map.remove(o) == PRESENT;
    }

    /**
     * Removes all of the elements from this set.
     */
    @Override
    public void clear() {
        map.clear();

            : Lists.<@Nullable Present<V>>newArrayListWithCapacity(futures.size());

    // Populate the results list with null initially.
    for (int i = 0; i < futures.size(); ++i) {
      values.add(null);
    }

    this.values = values;
  }

  @Override
  final void collectOneValue(int index, @ParametricNullness V returnValue) {
    @RetainedLocalRef List<@Nullable Present<V>> localValues = values;

  /**
   * Adds {@code node} if it is not already present.
   *
   * <p><b>Nodes must be unique</b>, just as {@code Map} keys must be. They must also be non-null.
   *
   * @return {@code true} if the graph was modified as a result of this call
   */
  @CanIgnoreReturnValue
  boolean addNode(N node);

  /**
   * Adds an edge connecting {@code nodeU} to {@code nodeV} if one is not already present.
   *

   * for an RPC may wait for a similar call that requests a long timeout, or a call by an
   * unprivileged user may return a resource accessible only to a privileged user making a similar
   * call. To prevent this problem, create a key object that includes all values that affect the
   * result of the query. Or use {@code LoadingCache.get(K)}, which lacks the ability to refer to
   * state other than that in the key.
   *

  @CollectionFeature.Require(SUPPORTS_REMOVE)
  public void testRemove_occurrences_present() {
    assertEquals(
        "multiset.remove(present, 2) didn't return the old count",
        1,
        getMultiset().remove(e0(), 2));
    assertFalse(
        "multiset contains present after multiset.remove(present, 2)",
        getMultiset().contains(e0()));
    assertEquals(0, getMultiset().count(e0()));
  }

  @CollectionSize.Require(SEVERAL)