}
  }

  @Override
  public @Nullable Entry<E> firstEntry() {
    return delegate().firstEntry();
  }

  /**
   * A sensible definition of {@link #firstEntry()} in terms of {@code entrySet().iterator()}.
   *
   * <p>If you override {@link #entrySet()}, you may wish to override {@link #firstEntry()} to
   * forward to this implementation.
   */

    assertEquals(c, sortedMultiset.tailMultiset(b.getElement(), CLOSED).firstEntry());
    assertEquals(c, sortedMultiset.tailMultiset(c.getElement(), CLOSED).firstEntry());
  }

  @CollectionSize.Require(SEVERAL)
  public void testHigher() {
    resetWithHole();
    assertEquals(c, sortedMultiset.tailMultiset(a.getElement(), OPEN).firstEntry());

    }
  }

  @Override
  public @Nullable Entry<E> firstEntry() {
    return delegate().firstEntry();
  }

  /**
   * A sensible definition of {@link #firstEntry()} in terms of {@code entrySet().iterator()}.
   *
   * <p>If you override {@link #entrySet()}, you may wish to override {@link #firstEntry()} to
   * forward to this implementation.
   */

    @Override
    public @Nullable E ceiling(@ParametricNullness E e) {
      return getElementOrNull(multiset().tailMultiset(e, CLOSED).firstEntry());
    }

    @Override
    public @Nullable E higher(@ParametricNullness E e) {
      return getElementOrNull(multiset().tailMultiset(e, OPEN).firstEntry());
    }

    @Override
    public NavigableSet<E> descendingSet() {

  }

  @Override
  public @Nullable Entry<K, V> ceilingEntry(@ParametricNullness K key) {
    return tailMap(key, true).firstEntry();
  }

  @Override
  public @Nullable Entry<K, V> higherEntry(@ParametricNullness K key) {
    return tailMap(key, false).firstEntry();
  }

  @Override
  public @Nullable K lowerKey(@ParametricNullness K key) {
    return Maps.keyOrNull(lowerEntry(key));
  }

    assertEquals(c, sortedMultiset.tailMultiset(b.getElement(), CLOSED).firstEntry());
    assertEquals(c, sortedMultiset.tailMultiset(c.getElement(), CLOSED).firstEntry());
  }

  @CollectionSize.Require(SEVERAL)
  public void testHigher() {
    resetWithHole();
    assertEquals(c, sortedMultiset.tailMultiset(a.getElement(), OPEN).firstEntry());

    return keyOrNull(higherEntry(key));
  }

  @Override
  public @Nullable Entry<K, V> firstEntry() {
    return delegate().firstEntry();
  }

  /**
   * A sensible definition of {@link #firstEntry} in terms of the {@code iterator()} of {@link
   * #entrySet}. If you override {@code entrySet}, you may wish to override {@code firstEntry} to
   * forward to this implementation.
   */

    return keyOrNull(higherEntry(key));
  }

  @Override
  public @Nullable Entry<K, V> firstEntry() {
    return delegate().firstEntry();
  }

  /**
   * A sensible definition of {@link #firstEntry} in terms of the {@code iterator()} of {@link
   * #entrySet}. If you override {@code entrySet}, you may wish to override {@code firstEntry} to
   * forward to this implementation.
   */

  @Override
  void init(int expectedSize, float loadFactor) {
    super.init(expectedSize, loadFactor);
    firstEntry = ENDPOINT;
    lastEntry = ENDPOINT;
    links = new long[expectedSize];
    Arrays.fill(links, UNSET);
  }

  @Override
  int firstIndex() {
    return (firstEntry == ENDPOINT) ? -1 : firstEntry;
  }

  @Override
  int nextIndex(int index) {
    int result = getSuccessor(index);

    }
  }

  @Override
  public @Nullable Entry<E> firstEntry() {
    return delegate().firstEntry();
  }

  /**
   * A sensible definition of {@link #firstEntry()} in terms of {@code entrySet().iterator()}.
   *
   * <p>If you override {@link #entrySet()}, you may wish to override {@link #firstEntry()} to
   * forward to this implementation.
   */