@Override
    public ValueSetLink<K, V> getPredecessorInValueSet() {
      return requireNonNull(predecessorInValueSet); // see the comment on the class fields
    }

    @Override
    public ValueSetLink<K, V> getSuccessorInValueSet() {
      return requireNonNull(successorInValueSet); // see the comment on the class fields
    }

    @Override
    public void setPredecessorInValueSet(ValueSetLink<K, V> entry) {

    void forceJdk() {
      requireNonNull(impl); // see the comment on the field
      this.impl = new JdkBackedSetBuilderImpl<>(impl);
    }

    final void copyIfNecessary() {
      if (forceCopy) {
        copy();
        forceCopy = false;
      }
    }

    void copy() {
      requireNonNull(impl); // see the comment on the field
      impl = impl.copy();
    }

    @Override

    checkSerialization(Predicates.equalTo(null));
  }

  /**
   * Tests for Predicates.instanceOf(x). TODO: Fix the comment style after fixing annotation
   * stripper to remove comments properly. Currently, all tests before the comments are removed as
   * well.
   */
  @GwtIncompatible // Predicates.instanceOf
  public void testIsInstanceOf_apply() {

      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);
    }

   */
  @CanIgnoreReturnValue
  public static int checkElementIndex(int index, int size, String desc) {
    // Carefully optimized for execution by hotspot (explanatory comment above)
    if (index < 0 || index >= size) {
      throw new IndexOutOfBoundsException(badElementIndex(index, size, desc));
    }
    return index;
  }

     */
    @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;
      }

      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));
  }

    links = null;
    return result;
  }

  /*
   * For discussion of the safety of the following methods for operating on predecessors and
   * successors, see the comments near the end of CompactHashMap, noting that the methods here call
   * link(), which is defined at the end of this file.
   */

  private int getPredecessor(int entry) {
    return ((int) (link(entry) >>> 32)) - 1;