* @since 11.0
   */
  public static <R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>
      Table<R, C, V> unmodifiableTable(Table<? extends R, ? extends C, ? extends V> table) {
    return new UnmodifiableTable<>(table);
  }

  private static class UnmodifiableTable<
          R extends @Nullable Object, C extends @Nullable Object, V extends @Nullable Object>

          @Nullable OutSpliteratorT prefix,
          Spliterator<InElementT> fromSplit,
          Function<? super InElementT, @Nullable OutSpliteratorT> function,
          int splitCharacteristics,
          long estSplitSize);
    }

    @Weak @Nullable OutSpliteratorT prefix;
    final Spliterator<InElementT> from;
    final Function<? super InElementT, @Nullable OutSpliteratorT> function;

    @Weak @Nullable OutSpliteratorT prefix;
    final Spliterator<InElementT> from;
    final Function<? super InElementT, @Nullable OutSpliteratorT> function;
    final Factory<InElementT, OutSpliteratorT> factory;
    int characteristics;
    long estimatedSize;

    FlatMapSpliterator(
        @Nullable OutSpliteratorT prefix,
        Spliterator<InElementT> from,
        Function<? super InElementT, @Nullable OutSpliteratorT> function,

  private static class SynchronizedMultimap<K extends @Nullable Object, V extends @Nullable Object>
      extends SynchronizedObject implements Multimap<K, V> {
    transient @Nullable Set<K> keySet;
    transient @Nullable Collection<V> valuesCollection;
    transient @Nullable Collection<Map.Entry<K, V>> entries;
    transient @Nullable Map<K, Collection<V>> asMap;
    transient @Nullable Multiset<K> keys;

    @SuppressWarnings("unchecked")

  private static class SynchronizedMultimap<K extends @Nullable Object, V extends @Nullable Object>
      extends SynchronizedObject implements Multimap<K, V> {
    transient @Nullable Set<K> keySet;
    transient @Nullable Collection<V> valuesCollection;
    transient @Nullable Collection<Map.Entry<K, V>> entries;
    transient @Nullable Map<K, Collection<V>> asMap;
    transient @Nullable Multiset<K> keys;

    @SuppressWarnings("unchecked")

  }

  private boolean containsMapping(
      @Nullable Object rowKey, @Nullable Object columnKey, @Nullable Object value) {
    return value != null && value.equals(get(rowKey, columnKey));
  }

  /** Remove a row key / column key / value mapping, if present. */
  private boolean removeMapping(
      @Nullable Object rowKey, @Nullable Object columnKey, @Nullable Object value) {
    if (containsMapping(rowKey, columnKey, value)) {

   */
  public static <A extends @Nullable Object, B extends @Nullable Object, C extends @Nullable Object>
      Function<A, C> compose(Function<B, C> g, Function<A, ? extends B> f) {
    return new FunctionComposition<>(g, f);
  }

  private static final class FunctionComposition<
          A extends @Nullable Object, B extends @Nullable Object, C extends @Nullable Object>
      implements Function<A, C>, Serializable {

    }
  }

  private static <E extends @Nullable Object> E getElementOrThrow(@Nullable Entry<E> entry) {
    if (entry == null) {
      throw new NoSuchElementException();
    }
    return entry.getElement();
  }

  private static <E extends @Nullable Object> @Nullable E getElementOrNull(
      @Nullable Entry<E> entry) {
    return (entry == null) ? null : entry.getElement();
  }

   * would lead to at least slighly more work at startup time.
   */
  @LazyInit private transient @Nullable Ordering<@Nullable Comparable<?>> nullsFirst;
  @LazyInit private transient @Nullable Ordering<@Nullable Comparable<?>> nullsLast;

  @Override
  @SuppressWarnings("unchecked") // TODO(kevinb): the right way to explain this??

   *
   * @since 20.0 (varargs overload since 2.0)
   */
  @CanIgnoreReturnValue
  public static <T> T checkNotNull(
      @Nullable T reference,
      String errorMessageTemplate,
      @Nullable Object p1,
      @Nullable Object p2,
      @Nullable Object p3,
      @Nullable Object p4) {
    if (reference == null) {
      throw new NullPointerException(Platform.lenientFormat(errorMessageTemplate, p1, p2, p3, p4));