* safe to do so. The exact circumstances under which a copy will or will not be performed are
   * undocumented and subject to change.
   *
   * @throws NullPointerException if any key or value in {@code multimap} is null
   */
  public static <K, V> ImmutableSetMultimap<K, V> copyOf(
      Multimap<? extends K, ? extends V> multimap) {
    return copyOf(multimap, null);
  }

  private static void testReverse(double[] input, double[] expectedOutput) {
    input = Arrays.copyOf(input, input.length);
    Doubles.reverse(input);
    assertThat(input).isEqualTo(expectedOutput);
  }

  private static void testReverse(
      double[] input, int fromIndex, int toIndex, double[] expectedOutput) {
    input = Arrays.copyOf(input, input.length);
    Doubles.reverse(input, fromIndex, toIndex);

  }

  private static void testReverse(long[] input, long[] expectedOutput) {
    input = Arrays.copyOf(input, input.length);
    Longs.reverse(input);
    assertThat(input).isEqualTo(expectedOutput);
  }

  private static void testReverse(long[] input, int fromIndex, int toIndex, long[] expectedOutput) {
    input = Arrays.copyOf(input, input.length);
    Longs.reverse(input, fromIndex, toIndex);

  private static void testReverse(short[] input, short[] expectedOutput) {
    input = Arrays.copyOf(input, input.length);
    Shorts.reverse(input);
    assertThat(input).isEqualTo(expectedOutput);
  }

  private static void testReverse(
      short[] input, int fromIndex, int toIndex, short[] expectedOutput) {
    input = Arrays.copyOf(input, input.length);
    Shorts.reverse(input, fromIndex, toIndex);

  }

  static <N, E> DirectedMultiNetworkConnections<N, E> ofImmutable(
      Map<E, N> inEdges, Map<E, N> outEdges, int selfLoopCount) {
    return new DirectedMultiNetworkConnections<>(
        ImmutableMap.copyOf(inEdges), ImmutableMap.copyOf(outEdges), selfLoopCount);
  }

  @LazyInit private transient @Nullable Reference<Multiset<N>> predecessorsReference;

  @Override
  public Set<N> predecessors() {

  }

  static <N, E> DirectedMultiNetworkConnections<N, E> ofImmutable(
      Map<E, N> inEdges, Map<E, N> outEdges, int selfLoopCount) {
    return new DirectedMultiNetworkConnections<>(
        ImmutableMap.copyOf(inEdges), ImmutableMap.copyOf(outEdges), selfLoopCount);
  }

  @LazyInit private transient @Nullable Reference<Multiset<N>> predecessorsReference;

  @Override
  public Set<N> predecessors() {

  // Unsafe, see ImmutableSortedMapFauxverideShim.
  @SuppressWarnings("unchecked")
  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));

    input = Arrays.copyOf(input, input.length);
    SignedBytes.sortDescending(input);
    assertThat(input).isEqualTo(expectedOutput);
  }

  private static void testSortDescending(
      byte[] input, int fromIndex, int toIndex, byte[] expectedOutput) {
    input = Arrays.copyOf(input, input.length);
    SignedBytes.sortDescending(input, fromIndex, toIndex);

        builder.put(entry.getKey(), entry.getValue());
      }
      return ImmutableMap.copyOf(builder);
    }
  }

  public static class ImmutableMapCopyOfEntriesGenerator extends TestStringMapGenerator {
    @Override
    protected Map<String, String> create(Entry<String, String>[] entries) {
      return ImmutableMap.copyOf(asList(entries));
    }
  }

  public static class ImmutableMapUnhashableValuesGenerator

  }

  static void testSort(long[] input, long[] expected) {
    input = Arrays.copyOf(input, input.length);
    UnsignedLongs.sort(input);
    assertThat(input).isEqualTo(expected);
  }

  static void testSort(long[] input, int from, int to, long[] expected) {
    input = Arrays.copyOf(input, input.length);
    UnsignedLongs.sort(input, from, to);
    assertThat(input).isEqualTo(expected);
  }