public static <K, V> ImmutableSortedMap<K, V> copyOf(Map<? extends K, ? extends V> map) {
    return copyOfInternal((Map<K, V>) map, (Ordering<K>) Ordering.natural());
  }

  public static <K, V> ImmutableSortedMap<K, V> copyOf(
      Map<? extends K, ? extends V> map, Comparator<? super K> comparator) {
    return copyOfInternal(map, checkNotNull(comparator));
  }

  // Unsafe, see ImmutableSortedMapFauxverideShim.

    // Hack around K not being a subtype of Comparable.
    // Unsafe, see ImmutableSortedSetFauxverideShim.
    @SuppressWarnings("unchecked")
    Ordering<K> naturalOrder = (Ordering<K>) NATURAL_ORDER;
    return copyOfInternal(map, naturalOrder);
  }

  /**
   * Returns an immutable map containing the same entries as {@code map}, with keys sorted by the
   * provided comparator.
   *

    // Hack around K not being a subtype of Comparable.
    // Unsafe, see ImmutableSortedSetFauxverideShim.
    @SuppressWarnings("unchecked")
    Ordering<K> naturalOrder = (Ordering<K>) NATURAL_ORDER;
    return copyOfInternal(map, naturalOrder);
  }

  /**
   * Returns an immutable map containing the same entries as {@code map}, with keys sorted by the
   * provided comparator.
   *