@GwtCompatible(serializable = true)
@SuppressWarnings({"unchecked", "rawtypes"}) // TODO(kevinb): the right way to explain this??
@ElementTypesAreNonnullByDefault
final class NaturalOrdering extends Ordering<Comparable<?>> implements Serializable {
  static final NaturalOrdering INSTANCE = new NaturalOrdering();

  // TODO: b/287198172 - Consider eagerly initializing these (but think about serialization).

  // TODO(kevinb): right way to explain this??
  // plus https://github.com/google/guava/issues/989
  public static <C extends Comparable> Ordering<C> natural() {
    return (Ordering<C>) NaturalOrdering.INSTANCE;
  }

  // Static factories

  /**
   * Returns an ordering based on an <i>existing</i> comparator instance. Note that it is

  // TODO(kevinb): right way to explain this??
  // plus https://github.com/google/guava/issues/989
  public static <C extends Comparable> Ordering<C> natural() {
    return (Ordering<C>) NaturalOrdering.INSTANCE;
  }

  // Static factories

  /**
   * Returns an ordering based on an <i>existing</i> comparator instance. Note that it is