* accepted (in which case it returns {@code true}). If it returns {@code false}, the {@code
   * Future} may have previously been set asynchronously, in which case its result may not be known
   * yet. That result, though not yet known, cannot be overridden by a call to a {@code set*}
   * method, only by a call to {@link #cancel}.
   *
   * <p>Beware of completing a future while holding a lock. Its listeners may do slow work or

      implements Supplier<T>, Serializable {
    final Supplier<T> delegate;
    final long durationNanos;
    @CheckForNull transient volatile T value;
    // The special value 0 means "not yet initialized".
    transient volatile long expirationNanos;

    ExpiringMemoizingSupplier(Supplier<T> delegate, long durationNanos) {
      this.delegate = delegate;
      this.durationNanos = durationNanos;
    }

    // Lock while we check state. We must maintain the lock while adding the new pair so that
    // another thread can't run the list out from under us. We only add to the list if we have not
    // yet started execution.
    synchronized (this) {
      if (!executed) {
        runnables = new RunnableExecutorPair(runnable, executor, runnables);
        return;
      }
    }

   *
   * <p>Entries in the map can be in the following states:
   *
   * <p>Valid: - Live: valid key/value are set
   *
   * <p>Invalid: - Collected: key/value was partially collected, but not yet cleaned up
   */
  interface InternalEntry<K, V, E extends InternalEntry<K, V, E>> {
    /** Gets the next entry in the chain. */
    E getNext();

    /** Gets the entry's hash. */
    int getHash();

    // * Everything with (to <= index < from) should be removed.
    // * The element with (index == from) should be kept.
    // * Everything with (index > from) has not been checked yet.

    // Check from the end of the list backwards (minimize expected cost of
    // moving elements when remove() is called). Stop before 'from' because
    // we already know that should be kept.

    @Deprecated
    @Override
    public final ImmutableSortedMap<K, V> buildKeepingLast() {
      // TODO(emcmanus): implement
      throw new UnsupportedOperationException(
          "ImmutableSortedMap.Builder does not yet implement buildKeepingLast()");
    }
  }

  private final transient RegularImmutableSortedSet<K> keySet;
  private final transient ImmutableList<V> valueList;

   * have started execution. This applies also to tasks given to {@code invokeAll} or {@code
   * invokeAny} which are pending serial execution, even the subset of the tasks that have not yet
   * started execution. It is unclear from the {@code ExecutorService} specification if these should
   * be included, and it's much easier to implement the interpretation that they not be. Finally, a

 * "https://github.com/google/guava/wiki/ImmutableCollectionsExplained">immutable collections</a>.
 *
 * @author Louis Wasserman
 * @since 12.0
 */
@GwtIncompatible // hasn't been tested yet
@ElementTypesAreNonnullByDefault
public abstract class ImmutableSortedMultiset<E> extends ImmutableMultiset<E>
    implements SortedMultiset<E> {
  // TODO(lowasser): GWT compatibility

  /**

      if (super.cancel(interruptIfRunning)) {
        /*
         * requireNonNull is generally safe: If cancel succeeded, then this Future was still
         * pending, so its `state` field hasn't been nulled out yet.
         *
         * OK, it's technically possible for this to fail in the presence of unsafe publishing, as
         * discussed in the comments in TimeoutFuture. TODO(cpovirk): Maybe check for null before

     * into any other.
     */
    SUBSUMED,

    /**
     * Some {@link ListenableFuture} has a callback attached that will close the {@link
     * CloseableList}, but it has not yet run. The {@link CloseableList} may not be subsumed.
     */
    WILL_CLOSE,

    /**
     * The callback that closes the {@link CloseableList} is running, but it has not completed. The