this.left = null;
      this.right = null;
    }

    /** Constructor for the header node. */
    AvlNode() {
      this.elem = null;
      this.elemCount = 1;
    }

    // For discussion of pred() and succ(), see the comment on the pred and succ fields.

    private AvlNode<E> pred() {
      return requireNonNull(pred);
    }

    private AvlNode<E> succ() {
      return requireNonNull(succ);

  void invalidate(@CompatibleWith("K") Object key);

  /**
   * Discards any cached values for keys {@code keys}.
   *
   * @since 11.0
   */
  // For discussion of <? extends Object>, see getAllPresent.
  void invalidateAll(Iterable<? extends Object> keys);

  /** Discards all entries in the cache. */
  void invalidateAll();

  }

  private static final class AboveAll extends Cut<Comparable<?>> {
    private static final AboveAll INSTANCE = new AboveAll();

    private AboveAll() {
      // For discussion of "", see BelowAll.
      super("");
    }

    @Override
    Comparable<?> endpoint() {
      throw new IllegalStateException("range unbounded on this side");
    }

    @Override

 * <p>No cascading checks are performed against the return values of methods unless the method is a
 * static factory method. Neither are semantics of mutation methods such as {@code
 * someList.add(obj)} checked. For more detailed discussion of supported and unsupported cases, see
 * {@link #testEquals}, {@link #testNulls} and {@link #testSerializable}.
 *
 * <p>For testing against the returned instances from a static factory class, such as
 *
 * <pre>

Aquí está lo que debes tener en cuenta y cómo revisar un pull request:

### Entiende el problema

* Primero, asegúrate de **entender el problema** que el pull request está intentando resolver. Podría tener una discusión más larga en una GitHub Discussion o issue.

* También hay una buena posibilidad de que el pull request no sea realmente necesario porque el problema se puede resolver de una manera **diferente**. Entonces puedes sugerir o preguntar sobre eso.

    }
    init(elementCount);
    for (int i = 0; i < elementCount; i++) {
      E element = (E) stream.readObject();
      add(element);
    }
  }

  /*
   * For discussion of the safety of the following methods, see the comments near the end of
   * CompactHashMap.
   */

  private Object requireTable() {
    return requireNonNull(table);
  }

   *
   * <p>Cancelling the pipeline will not cancel {@code future}, so that the pipeline can access its
   * value in order to close it.
   *
   * @param future the future to create the {@code ClosingFuture} from. For discussion of the
   *     future's result type {@code C}, see {@link DeferredCloser#eventuallyClose(Object,
   *     Executor)}.
   * @param closingExecutor the future's result will be closed on this executor

  //    the initial write (just stronger guarantees if it does).
  //
  // See: http://cs.oswego.edu/pipermail/concurrency-interest/2015-January/013800.html
  // For a (long) discussion about this specific issue and the general futility of life.
  //
  // For the time being we are OK with the problem discussed above since it requires a caller to

   * logged.
   *
   * <p>When selecting an executor, note that {@code directExecutor} is dangerous in some cases. See
   * the discussion in the {@link ListenableFuture#addListener ListenableFuture.addListener}
   * documentation.
   *
   * @param listener the listener to run when the manager changes state

        this.value = value;
      }

      T get() {
        /*
         * requireNonNull is safe because we call get() only if we've previously called set().
         *
         * (For further discussion of nullness, see the comment above the method.)
         */
        return requireNonNull(value);
      }
    }
    OptionalState state = new OptionalState();