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

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

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

import javax.annotation.CheckForNull;

/**
 * Implementation of {@code Table} whose row keys and column keys are ordered by their natural
 * ordering or by supplied comparators. When constructing a {@code TreeBasedTable}, you may provide
 * comparators for the row keys and the column keys, or you may use natural ordering for both.
 *
 * <p>The {@link #rowKeySet} method returns a {@link SortedSet} and the {@link #rowMap} method

 *
 * @author Chris Povirk
 * @author Jared Levy
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public abstract class TestIntegerSortedSetGenerator extends TestIntegerSetGenerator {
  @Override
  protected abstract SortedSet<Integer> create(Integer[] elements);

  /** Sorts the elements by their natural ordering. */
  @Override

 *
 * @author Chris Povirk
 * @author Jared Levy
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public abstract class TestIntegerSortedSetGenerator extends TestIntegerSetGenerator {
  @Override
  protected abstract SortedSet<Integer> create(Integer[] elements);

  /** Sorts the elements by their natural ordering. */
  @Override

import javax.annotation.CheckForNull;

/**
 * Implementation of {@code Table} whose row keys and column keys are ordered by their natural
 * ordering or by supplied comparators. When constructing a {@code TreeBasedTable}, you may provide
 * comparators for the row keys and the column keys, or you may use natural ordering for both.
 *
 * <p>The {@link #rowKeySet} method returns a {@link SortedSet} and the {@link #rowMap} method

            .allowsSelfLoops(true)
            .nodeOrder(ElementOrder.<String>natural())
            .immutable()
            .build();

    assertThat(emptyGraph.isDirected()).isTrue();
    assertThat(emptyGraph.allowsSelfLoops()).isTrue();
    assertThat(emptyGraph.nodeOrder()).isEqualTo(ElementOrder.<String>natural());
  }

  /**

            .allowsSelfLoops(true)
            .nodeOrder(ElementOrder.<String>natural())
            .immutable()
            .build();

    assertThat(emptyGraph.isDirected()).isTrue();
    assertThat(emptyGraph.allowsSelfLoops()).isTrue();
    assertThat(emptyGraph.nodeOrder()).isEqualTo(ElementOrder.<String>natural());
  }

  /**

   * ordering.
   *
   * @throws NullPointerException if any element is null
   */
  public static <E extends Comparable<? super E>> ImmutableSortedMultiset<E> of(E e1, E e2, E e3) {
    return copyOf(Ordering.natural(), Arrays.asList(e1, e2, e3));
  }

  /**
   * Returns an immutable sorted multiset containing the given elements sorted by their natural
   * ordering.
   *

  /**
   * Creates an empty {@code TreeMultimap} ordered by the natural ordering of its keys and values.
   */
  @SuppressWarnings("rawtypes") // https://github.com/google/guava/issues/989
  public static <K extends Comparable, V extends Comparable> TreeMultimap<K, V> create() {
    return new TreeMultimap<>(Ordering.natural(), Ordering.natural());
  }

  /**

import com.google.common.annotations.GwtCompatible;
import java.util.Collections;
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> {