* @since 14.0
   */
  public static <C extends Comparable<?>> Range<C> encloseAll(Iterable<C> values) {
    checkNotNull(values);
    if (values instanceof SortedSet) {
      SortedSet<C> set = (SortedSet<C>) values;
      Comparator<?> comparator = set.comparator();
      if (Ordering.<C>natural().equals(comparator) || comparator == null) {
        return closed(set.first(), set.last());
      }

      return (SortedMap<K, V>) unfiltered;
    }

    @Override
    public SortedSet<K> keySet() {
      return (SortedSet<K>) super.keySet();
    }

    @Override
    SortedSet<K> createKeySet() {
      return new SortedKeySet();
    }

    @WeakOuter
    class SortedKeySet extends KeySet implements SortedSet<K> {
      @Override
      @CheckForNull

      return (SortedMap<K, V>) unfiltered;
    }

    @Override
    public SortedSet<K> keySet() {
      return (SortedSet<K>) super.keySet();
    }

    @Override
    SortedSet<K> createKeySet() {
      return new SortedKeySet();
    }

    @WeakOuter
    class SortedKeySet extends KeySet implements SortedSet<K> {
      @Override
      @CheckForNull

  private static final class TreeSetSupplier<V extends @Nullable Object>
      implements Supplier<SortedSet<V>>, Serializable {
    private final Comparator<? super V> comparator;

    TreeSetSupplier(Comparator<? super V> comparator) {
      this.comparator = checkNotNull(comparator);
    }

    @Override
    public SortedSet<V> get() {
      return new TreeSet<>(comparator);
    }
  }

import com.google.common.testing.SerializableTester;
import java.util.Collection;
import java.util.Comparator;
import java.util.Iterator;
import java.util.Map.Entry;
import java.util.SortedSet;
import junit.framework.TestCase;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Unit tests for {@code TreeMultimap} with explicit comparators.
 *
 * @author Jared Levy
 */

    assertThrows(NoSuchElementException.class, () -> Iterables.getLast(list));
  }

  public void testGetLast_sortedSet() {
    SortedSet<String> sortedSet = ImmutableSortedSet.of("b", "c", "a");
    assertEquals("c", Iterables.getLast(sortedSet));
  }

  public void testGetLast_withDefault_singleton() {
    Iterable<String> iterable = singletonList("foo");

     * to know they are SortedSets and probably would not call this method.
     */
    if (iterable instanceof SortedSet) {
      SortedSet<E> sortedSet = (SortedSet<E>) iterable;
      return Optional.of(sortedSet.last());
    }

    while (true) {
      E current = iterator.next();
      if (!iterator.hasNext()) {
        return Optional.of(current);
      }

      }
    } else {
      for (int i = 0; i < reps; i++) {
        dummy += ORDERING.immutableSortedCopy(input).get(0);
      }
    }
    return dummy;
  }

  @Benchmark
  int sortedSet(int reps) {
    int dummy = 0;
    if (mutable) {
      for (int i = 0; i < reps; i++) {
        dummy += new TreeSet<Integer>(input).first();
      }
    } else {
      for (int i = 0; i < reps; i++) {

import java.util.Iterator;
import java.util.List;
import java.util.Map.Entry;
import java.util.NavigableMap;
import java.util.NavigableSet;
import java.util.Set;
import java.util.SortedMap;
import java.util.SortedSet;
import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;

/**
 * Unit tests for {@code TreeMultimap} with natural ordering.
 *
 * @author Jared Levy
 */

import java.util.Map;
import java.util.NavigableMap;
import java.util.NavigableSet;
import java.util.Queue;
import java.util.Random;
import java.util.Set;
import java.util.SortedMap;
import java.util.SortedSet;
import java.util.UUID;
import java.util.concurrent.BlockingDeque;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;