@GwtCompatible(serializable = true)
@ElementTypesAreNonnullByDefault
final class ExplicitOrdering<T> extends Ordering<T> implements Serializable {
  final ImmutableMap<T, Integer> rankMap;

  ExplicitOrdering(List<T> valuesInOrder) {
    this(Maps.indexMap(valuesInOrder));
  }

  ExplicitOrdering(ImmutableMap<T, Integer> rankMap) {
    this.rankMap = rankMap;
  }

  @Override

@GwtCompatible(serializable = true)
@ElementTypesAreNonnullByDefault
final class ExplicitOrdering<T> extends Ordering<T> implements Serializable {
  final ImmutableMap<T, Integer> rankMap;

  ExplicitOrdering(List<T> valuesInOrder) {
    this(Maps.indexMap(valuesInOrder));
  }

  ExplicitOrdering(ImmutableMap<T, Integer> rankMap) {
    this.rankMap = rankMap;
  }

  @Override

   *     (according to {@link Object#equals})
   */
  // TODO(kevinb): provide replacement
  @GwtCompatible(serializable = true)
  public static <T> Ordering<T> explicit(List<T> valuesInOrder) {
    return new ExplicitOrdering<>(valuesInOrder);
  }

  /**
   * Returns an ordering that compares objects according to the order in which they are given to