public static <T extends @Nullable Object, S extends T> Comparator<Iterable<S>> lexicographical(
      Comparator<T> comparator) {
    return new LexicographicalOrdering<S>(checkNotNull(comparator));
  }

  /**
   * Returns {@code true} if each element in {@code iterable} after the first is greater than or
   * equal to the element that preceded it, according to the specified comparator. Note that this is

    @SuppressWarnings({"unchecked", "nullness"})
    Comparator<@Nullable Object> unsafeComparator = (Comparator<@Nullable Object>) comparator;
    return unsafeComparator.compare(a, b);
  }

  final transient Comparator<? super E> comparator;

  ImmutableSortedSet(Comparator<? super E> comparator) {
    this.comparator = comparator;
  }

  /**

   * Comparator}.
   *
   * @throws NullPointerException if {@code comparator} or any of {@code elements} is null
   */
  public static <E> ImmutableSortedMultiset<E> copyOf(
      Comparator<? super E> comparator, Iterator<? extends E> elements) {
    checkNotNull(comparator);
    return new Builder<E>(comparator).addAll(elements).build();
  }

  /**

  public static <K, V> ImmutableSortedMap<K, V> copyOfSorted(SortedMap<K, ? extends V> map) {
    Comparator<? super K> comparator = map.comparator();
    if (comparator == null) {
      // If map has a null comparator, the keys should have a natural ordering,
      // even though K doesn't explicitly implement Comparable.
      comparator = (Comparator<? super K>) NATURAL_ORDER;
    }
    if (map instanceof ImmutableSortedMap) {

  }

  /**
   * Returned by get() when a missing key is provided. Also holds the comparator, if any, used for
   * values.
   */
  private final transient ImmutableSet<V> emptySet;

  ImmutableSetMultimap(
      ImmutableMap<K, ImmutableSet<V>> map,
      int size,
      @CheckForNull Comparator<? super V> valueComparator) {
    super(map, size);
    this.emptySet = emptySet(valueComparator);
  }

    @LazyInit @CheckForNull private transient Comparator<? super K> comparator;

    @SuppressWarnings("unchecked")
    @Override
    public Comparator<? super K> comparator() {
      Comparator<? super K> result = comparator;
      if (result == null) {
        Comparator<? super K> forwardCmp = forward().comparator();
        if (forwardCmp == null) {
          forwardCmp = (Comparator) Ordering.natural();
        }

      return standardTailSet(fromElement);
    }

    @SuppressWarnings("unchecked")
    @Override
    public Comparator<? super E> comparator() {
      Comparator<? super E> forwardComparator = forward.comparator();
      if (forwardComparator == null) {
        return (Comparator) Ordering.natural().reverse();
      } else {
        return reverse(forwardComparator);
      }
    }

   * @since 11.0
   */
  @DoNotMock
  public static final class Builder<R, C, V> {
    private final List<Cell<R, C, V>> cells = Lists.newArrayList();
    @CheckForNull private Comparator<? super R> rowComparator;
    @CheckForNull private Comparator<? super C> columnComparator;

    /**
     * Creates a new builder. The returned builder is equivalent to the builder generated by {@link
     * ImmutableTable#builder}.
     */

   * {@code ImmutableList}, use {@code stream.sorted(comparator).collect(toImmutableList())}.
   *
   * @throws NullPointerException if any element in the input is null
   * @since 21.0
   */
  public static <E> ImmutableList<E> sortedCopyOf(
      Comparator<? super E> comparator, Iterable<? extends E> elements) {
    checkNotNull(comparator);
    @SuppressWarnings("unchecked") // all supported methods are covariant

import java.io.ObjectInputStream;
import java.io.Serializable;
import java.util.AbstractMap;
import java.util.Arrays;
import java.util.BitSet;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.SortedMap;
import java.util.function.BinaryOperator;