if (o.isPresent()) {
                had++;
                items.addAll(o.get());
            }
        }
        return had == 0 ? Optional.empty() : Optional.of(List.copyOf(items));
    }

    protected Optional<Map<String, String>> collectMapIfPresentOrEmpty(
            Function<O, Optional<Map<String, String>>> getter) {
        int had = 0;

  @Override
  protected <E extends Comparable<? super E>> Set<E> copyOf(E[] elements) {
    return ImmutableSet.copyOf(elements);
  }

  @Override
  protected <E extends Comparable<? super E>> Set<E> copyOf(Collection<? extends E> elements) {
    return ImmutableSet.copyOf(elements);
  }

  @Override
  protected <E extends Comparable<? super E>> Set<E> copyOf(Iterable<? extends E> elements) {

  @After
  public final void validateGraphState() {
    validateGraph(graph);
  }

  static <N> void validateGraph(Graph<N> graph) {
    assertStronglyEquivalent(graph, Graphs.copyOf(graph));
    assertStronglyEquivalent(graph, ImmutableGraph.copyOf(graph));

    String graphString = graph.toString();
    assertThat(graphString).contains("isDirected: " + graph.isDirected());

     */
    assertThat(ImmutableDoubleArray.copyOf(new double[0]))
        .isSameInstanceAs(ImmutableDoubleArray.of());
  }

  public void testCopyOf_array_nonempty() {
    double[] array = new double[] {0, 1, 3};
    ImmutableDoubleArray iia = ImmutableDoubleArray.copyOf(array);
    array[2] = 2;
    assertThat(iia.asList()).containsExactly(0.0, 1.0, 3.0).inOrder();
  }

    ImmutableList<Cell<R, C, V>> cellList = ImmutableList.copyOf(cells);
    for (Cell<R, C, V> cell : cells) {
      rowSpaceBuilder.add(cell.getRowKey());
      columnSpaceBuilder.add(cell.getColumnKey());
    }

    ImmutableSet<R> rowSpace =
        (rowComparator == null)
            ? ImmutableSet.copyOf(rowSpaceBuilder)
            : ImmutableSet.copyOf(ImmutableList.sortedCopyOf(rowComparator, rowSpaceBuilder));

      rowBuilder.put(row.getKey(), ImmutableMap.copyOf(row.getValue()));
    }
    this.rowMap = rowBuilder.buildOrThrow();

    ImmutableMap.Builder<C, ImmutableMap<R, V>> columnBuilder =
        new ImmutableMap.Builder<>(columns.size());
    for (Entry<C, Map<R, V>> col : columns.entrySet()) {
      columnBuilder.put(col.getKey(), ImmutableMap.copyOf(col.getValue()));
    }

    return copyOf(elements);
  }

  public static <E> ImmutableList<E> copyOf(Iterable<? extends E> elements) {
    checkNotNull(elements); // for GWT
    return (elements instanceof Collection)
        ? copyOf((Collection<? extends E>) elements)
        : copyOf(elements.iterator());
  }

  public static <E> ImmutableList<E> copyOf(Iterator<? extends E> elements) {

  }

  @Test
  public void copyOfImmutableNetwork_optimized() {
    Network<String, String> network1 =
        ImmutableNetwork.copyOf(NetworkBuilder.directed().<String, String>build());
    Network<String, String> network2 = ImmutableNetwork.copyOf(network1);

    assertThat(network2).isSameInstanceAs(network1);
  }

  @Test
  public void edgesConnecting_directed() {

 * each immutable-collection class. This ensures, for example, that a call written "{@code
 * ImmutableSortedSet.copyOf()}" cannot secretly be a call to {@code ImmutableSet.copyOf()}.
 *
 * @author Chris Povirk
 */
@NullUnmarked
public class FauxveridesTest extends TestCase {
  public void testImmutableBiMap() {

 * each immutable-collection class. This ensures, for example, that a call written "{@code
 * ImmutableSortedSet.copyOf()}" cannot secretly be a call to {@code ImmutableSet.copyOf()}.
 *
 * @author Chris Povirk
 */
@NullUnmarked
public class FauxveridesTest extends TestCase {
  public void testImmutableBiMap() {