if (result == null) {
      return comparator = Ordering.from(forwardMultiset().comparator()).<E>reverse();
    }
    return result;
  }

  @Nullable private transient SortedSet<E> elementSet;

  @Override
  public SortedSet<E> elementSet() {
    SortedSet<E> result = elementSet;
    if (result == null) {
      return elementSet = new SortedMultisets.ElementSet<E>(this);
    }
    return result;
  }

  @Override

  }

  public void testFirst_sortedSet() {
    SortedSet<String> sortedSet = ImmutableSortedSet.of("b", "c", "a");
    assertThat(FluentIterable.from(sortedSet).first()).hasValue("a");
  }

  public void testFirst_emptySortedSet() {
    SortedSet<String> sortedSet = ImmutableSortedSet.of();
    assertThat(FluentIterable.from(sortedSet).first()).isAbsent();
  }

      allEntries.addAll(extremeValues);
      allEntries.addAll(normalValues);
      SortedSet<E> set = delegate.create(allEntries.toArray());

      return createSubSet(set, firstExclusive, lastExclusive);
    }

    /** Calls the smallest subSet overload that filters out the extreme values. */
    SortedSet<E> createSubSet(SortedSet<E> set, E firstExclusive, E lastExclusive) {

      return new SortedAsMap(sortedMap().tailMap(fromKey));
    }

    @CheckForNull SortedSet<K> sortedKeySet;

    // returns a SortedSet, even though returning a Set would be sufficient to
    // satisfy the SortedMap.keySet() interface
    @Override
    public SortedSet<K> keySet() {
      SortedSet<K> result = sortedKeySet;
      return (result == null) ? sortedKeySet = createKeySet() : result;
    }

import java.util.List;
import java.util.SortedSet;

/**
 * Create string sets for testing collections that are sorted by natural ordering.
 *
 * @author Jared Levy
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public abstract class TestStringSortedSetGenerator extends TestStringSetGenerator
    implements TestSortedSetGenerator<String> {

  @Override
  public SortedSet<String> create(Object... elements) {

  public Test testsForTreeSetWithComparator() {
    return NavigableSetTestSuiteBuilder.using(
            new TestStringSortedSetGenerator() {
              @Override
              public SortedSet<String> create(String[] elements) {
                SortedSet<String> set = new TreeSet<>(arbitraryNullFriendlyComparator());
                Collections.addAll(set, elements);
                return set;
              }
            })

    }

    @Override
    public @Nullable T pollLast() {
      return standardPollLast();
    }

    @Override
    public SortedSet<T> headSet(T toElement) {
      return standardHeadSet(toElement);
    }

    @Override
    public SortedSet<T> tailSet(T fromElement) {
      return standardTailSet(fromElement);
    }
  }

  public static Test suite() {

import java.util.SortedMap;
import java.util.SortedSet;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Basic implementation of a {@link SortedSetMultimap} with a sorted key set.
 *
 * <p>This superclass allows {@code TreeMultimap} to override methods to return navigable set and
 * map types in non-GWT only, while GWT code will inherit the SortedMap/SortedSet overrides.
 *
 * @author Louis Wasserman
 */

 */

package com.google.common.collect;

import java.util.Comparator;
import java.util.SortedSet;
import javax.annotation.CheckForNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * GWT emulation of {@code SortedMultiset}, with {@code elementSet} reduced to returning a {@code
 * SortedSet} for GWT compatibility.
 *
 * @author Louis Wasserman
 * @since 11.0
 */

      return new SortedAsMap(sortedMap().tailMap(fromKey));
    }

    @CheckForNull SortedSet<K> sortedKeySet;

    // returns a SortedSet, even though returning a Set would be sufficient to
    // satisfy the SortedMap.keySet() interface
    @Override
    public SortedSet<K> keySet() {
      SortedSet<K> result = sortedKeySet;
      return (result == null) ? sortedKeySet = createKeySet() : result;
    }