final Monitor monitor = this.monitor;
    monitor.enter();
    try {
      return count;
    } finally {
      monitor.leave();
    }
  }

  // this doc comment is a modified copy of the inherited doc comment,
  // without the reference to unlimited queues.
  /**
   * Returns the number of additional elements that this queue can ideally (in the absence of memory

      boilerplate notice, with the fields enclosed by brackets "[]"
      replaced with your own identifying information. (Don't include
      the brackets!)  The text should be enclosed in the appropriate
      comment syntax for the file format. We also recommend that a
      file or class name and description of purpose be included on the
      same "printed page" as the copyright notice for easier

 * requirement that existing callers already fulfill).
 *
 * Disclaimer: Part of the reason that callers are so well adapted to `Function<A, B>` may be that
 * that is how the signature looked even prior to this comment! So naturally any change can break
 * existing users, but it can't *fix* existing users because any users who needed
 * `Function<@Nullable A, @Nullable B>` already had to find a workaround. Still, there is a *ton* of

     */
    @CanIgnoreReturnValue
    public Builder<E> addCopies(E element, int occurrences) {
      requireNonNull(contents); // see the comment on the field
      if (occurrences == 0) {
        return this;
      }
      if (buildInvoked) {
        contents = new ObjectCountHashMap<E>(contents);
        isLinkedHash = false;
      }

       */
      KeyList<K, V> keyList = requireNonNull(keyToKeyList.remove(node.key));
      keyList.count = 0;
      modCount++;
    } else {
      // requireNonNull is safe (under the conditions listed in the comment in the branch above).
      KeyList<K, V> keyList = requireNonNull(keyToKeyList.get(node.key));
      keyList.count--;

      if (node.previousSibling == null) {

  }

  /**
   * These tests fail in JDK 9 and JDK 10 for an unknown reason. It might be the test; it might be
   * the underlying functionality. Fixing this is not a high priority; if you need it to be fixed,
   * please comment on <a href="https://github.com/google/guava/issues/3086">issue 3086</a>.
   */
  private static boolean isJdk9OrHigher() {
    return JAVA_SPECIFICATION_VERSION.value().startsWith("9")

    final Monitor monitor = this.monitor;
    monitor.enter();
    try {
      return count;
    } finally {
      monitor.leave();
    }
  }

  // this doc comment is a modified copy of the inherited doc comment,
  // without the reference to unlimited queues.
  /**
   * Returns the number of additional elements that this queue can ideally (in the absence of memory

      checkPositive(++successorCount);

      if (orderedNodeConnections != null) {
        orderedNodeConnections.add(new NodeConnection.Succ<>(node));
      }
    }

    // See the comment on the similar cast in removeSuccessor.
    return previousSuccessor == null ? null : (V) previousSuccessor;
  }

  private static boolean isPredecessor(@CheckForNull Object value) {

    /*
     * If greatestOf() promised to be implemented as reverse().leastOf(), this
     * test would be enough. It doesn't... but we'll cheat and act like it does
     * anyway. There's a comment there to remind us to fix this if we change it.
     */
    List<Integer> list = Arrays.asList(3, 1, 3, 2, 4, 2, 4, 3);
    assertEquals(Arrays.asList(4, 4, 3, 3), numberOrdering.greatestOf(list, 4));
  }

    /*
     * If greatestOf() promised to be implemented as reverse().leastOf(), this
     * test would be enough. It doesn't... but we'll cheat and act like it does
     * anyway. There's a comment there to remind us to fix this if we change it.
     */
    List<Integer> list = Arrays.asList(3, 1, 3, 2, 4, 2, 4, 3);
    assertEquals(Arrays.asList(4, 4, 3, 3), numberOrdering.greatestOf(list, 4));
  }