}
    }
    return dummy;
  }

  @Benchmark
  int ordering(int reps) {
    int dummy = 0;
    if (mutable) {
      for (int i = 0; i < reps; i++) {
        dummy += ORDERING.sortedCopy(input).get(0);
      }
    } else {
      for (int i = 0; i < reps; i++) {
        dummy += ORDERING.immutableSortedCopy(input).get(0);
      }
    }
    return dummy;
  }

   */
  private static final Comparator<?> NATURAL_ORDER = Ordering.natural();

  private static final ImmutableSortedMap<Comparable<?>, Object> NATURAL_EMPTY_MAP =
      new ImmutableSortedMap<>(ImmutableSortedSet.emptySet(Ordering.natural()), ImmutableList.of());

  static <K, V> ImmutableSortedMap<K, V> emptyMap(Comparator<? super K> comparator) {
    if (Ordering.natural().equals(comparator)) {
      return of();
    } else {

import org.jspecify.annotations.Nullable;

/**
 * An ordering that orders elements by applying an order to the result of a function on those
 * elements.
 */
@GwtCompatible
final class ByFunctionOrdering<F extends @Nullable Object, T extends @Nullable Object>
    extends Ordering<F> implements Serializable {
  final Function<F, ? extends T> function;
  final Ordering<T> ordering;

    assertEquals(tree, copyFromTree);
    assertThat(copyFromTree.keyComparator()).isEqualTo(Ordering.natural());
    assertThat(copyFromTree.valueComparator()).isEqualTo(Ordering.natural());
    assertThat(copyFromTree.get(1.0).comparator()).isEqualTo(Ordering.natural());
  }

  /** Test that creating one TreeMultimap from a non-TreeMultimap results in natural ordering. */
  public void testCreateFromHashMultimap() {

    // Unsafe, see ImmutableSortedMultisetFauxverideShim.
    @SuppressWarnings("unchecked")
    Ordering<E> naturalOrder = (Ordering<E>) Ordering.<Comparable<?>>natural();
    return copyOf(naturalOrder, elements);
  }

  /**
   * Returns an immutable sorted multiset containing the given elements sorted by their natural
   * ordering.
   *
   * <p>This method is not type-safe, as it may be called on elements that are not mutually

import java.io.Serializable;
import java.util.Iterator;
import org.jspecify.annotations.Nullable;

/** An ordering that uses the reverse of a given order. */
@GwtCompatible
final class ReverseOrdering<T extends @Nullable Object> extends Ordering<T>
    implements Serializable {
  final Ordering<? super T> forwardOrder;

  ReverseOrdering(Ordering<? super T> forwardOrder) {
    this.forwardOrder = checkNotNull(forwardOrder);
  }

  @Override

  }

  @SuppressWarnings("unchecked")
  @Override
  public <S extends @Nullable Object> Ordering<S> reverse() {
    return (Ordering<S>) this;
  }

  private Object readResolve() {
    return INSTANCE;
  }

  @Override
  public String toString() {
    return "Ordering.allEqual()";
  }

  @GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 0;

  }

  @SuppressWarnings("unchecked")
  @Override
  public <S extends @Nullable Object> Ordering<S> reverse() {
    return (Ordering<S>) this;
  }

  private Object readResolve() {
    return INSTANCE;
  }

  @Override
  public String toString() {
    return "Ordering.allEqual()";
  }

  @GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 0;

  @SuppressWarnings("unchecked")
  static final Comparator<?> NATURAL_ORDER = Ordering.natural();

  private final transient SortedMap<K, V> sortedDelegate;

  // The comparator used by this map.  It's the same as that of sortedDelegate,
  // except that when sortedDelegate's comparator is null, it points to a
  // non-null instance of Ordering.natural().
  // (cpovirk: Is sortedDelegate's comparator really ever null?)

  @WeakOuter
  private final class Heap {
    final Ordering<E> ordering;

    @SuppressWarnings("nullness:initialization.field.uninitialized")
    @Weak
    Heap otherHeap; // always initialized immediately after construction

    Heap(Ordering<E> ordering) {
      this.ordering = ordering;
    }

    int compareElements(int a, int b) {
      return ordering.compare(elementData(a), elementData(b));
    }