* build-system quirks.
   */
  private @interface GwtTransient {}

  /**
   * Compares strings in natural order except that null comes immediately before a given value. This
   * works better than Ordering.natural().nullsFirst() because, if null comes before all other
   * values, it lies outside the submap/submultiset ranges we test, and the variety of tests that

        Collections.addAll(multiset, elements);
        return multiset;
      }

      @Override
      public List<String> order(List<String> insertionOrder) {
        return Ordering.natural().sortedCopy(insertionOrder);
      }
    };
  }

  private static final String KEY = "puppies";

  ConcurrentMap<String, AtomicInteger> backingMap;
  ConcurrentHashMultiset<String> multiset;

  }

  // LinkedList: see {@link com.google.common.collect.Lists}

  // PriorityBlockingQueue

  /**
   * Creates an empty {@code PriorityBlockingQueue} with the ordering given by its elements' natural
   * ordering.
   *
   * @since 11.0 (but the bound of {@code E} was changed from {@code Object} to {@code Comparable}
   *     in 15.0)
   */

    T upperEndpoint = range.hasUpperBound() ? range.upperEndpoint() : null;
    BoundType upperBoundType = range.hasUpperBound() ? range.upperBoundType() : OPEN;
    return new GeneralRange<>(
        Ordering.natural(),
        range.hasLowerBound(),
        lowerEndpoint,
        lowerBoundType,
        range.hasUpperBound(),
        upperEndpoint,
        upperBoundType);
  }

    return create(Range.closedOpen(lower, upper), DiscreteDomain.longs());
  }

  final DiscreteDomain<C> domain;

  ContiguousSet(DiscreteDomain<C> domain) {
    super(Ordering.natural());
    this.domain = domain;
  }

  @Override
  public ContiguousSet<C> headSet(C toElement) {
    return headSetImpl(checkNotNull(toElement), false);
  }

  /** @since 12.0 */

final class RegularImmutableSortedSet<E> extends ImmutableSortedSet<E> {
  static final RegularImmutableSortedSet<Comparable> NATURAL_EMPTY_SET =
      new RegularImmutableSortedSet<>(ImmutableList.<Comparable>of(), Ordering.natural());

  private final transient ImmutableList<E> elements;

  RegularImmutableSortedSet(ImmutableList<E> elements, Comparator<? super E> comparator) {
    super(comparator);
    this.elements = elements;
  }

 * invoke methods, they invoke methods on the {@code ForwardingNavigableSet}.
 *
 * <p>Each of the {@code standard} methods uses the set's comparator (or the natural ordering of the
 * elements, if there is no comparator) to test element equality. As a result, if the comparator is
 * not consistent with equals, some of the standard implementations may violate the {@code Set}
 * contract.
 *

    T upperEndpoint = range.hasUpperBound() ? range.upperEndpoint() : null;
    BoundType upperBoundType = range.hasUpperBound() ? range.upperBoundType() : OPEN;
    return new GeneralRange<>(
        Ordering.natural(),
        range.hasLowerBound(),
        lowerEndpoint,
        lowerBoundType,
        range.hasUpperBound(),
        upperEndpoint,
        upperBoundType);
  }

                    return unmodifiableNavigableSet(set);
                  }

                  @Override
                  public List<String> order(List<String> insertionOrder) {
                    return Ordering.natural().sortedCopy(insertionOrder);
                  }
                })
            .named("Sets.unmodifiableNavigableSet[TreeSet]")
            .withFeatures(

   *
   * <p>An empty iterable has only one permutation, which is an empty list.
   *
   * <p>This method is equivalent to {@code Collections2.orderedPermutations(list,
   * Ordering.natural())}.
   *
   * @param elements the original iterable whose elements have to be permuted.
   * @return an immutable {@link Collection} containing all the different permutations of the
   *     original iterable.