Collection<E> collection = (Collection<E>) elements;
      if (collection.isEmpty()) {
        return ImmutableSet.of();
      } else {
        return ImmutableEnumSet.asImmutable(EnumSet.copyOf(collection));
      }
    } else {
      Iterator<E> itr = elements.iterator();
      if (itr.hasNext()) {
        EnumSet<E> enumSet = EnumSet.of(itr.next());
        Iterators.addAll(enumSet, itr);

            op.setup(form -> {
                groupService.getGroup(id).ifPresent(entity -> {
                    copyBeanToBean(entity, form, copyOp -> {
                        copyOp.excludeNull();
                    });
                    form.crudMode = crudMode;
                }).orElse(() -> {

      apply {
        require(tls) { "no cipher suites for cleartext connections" }
        require(cipherSuites.isNotEmpty()) { "At least one cipher suite is required" }

        this.cipherSuites = cipherSuites.copyOf() as Array<String> // Defensive copy.
      }

    fun allEnabledTlsVersions() =
      apply {
        require(tls) { "no TLS versions for cleartext connections" }
        this.tlsVersions = null
      }

  // TODO(cpovirk): should we reject null items, since the tests already check null automatically?
  @CanIgnoreReturnValue
  public RelationshipTester<T> addRelatedGroup(Iterable<? extends T> group) {
    groups.add(ImmutableList.copyOf(group));
    return this;
  }

  public void test() {
    for (int groupNumber = 0; groupNumber < groups.size(); groupNumber++) {
      ImmutableList<T> group = groups.get(groupNumber);

      return false;
    }

    // Since views are returned, we need to copy the edges that will be removed.
    // Thus we avoid modifying the underlying view while iterating over it.
    for (E edge : ImmutableList.copyOf(connections.incidentEdges())) {
      removeEdge(edge);
    }
    nodeConnections.remove(node);
    return true;
  }

  @Override
  @CanIgnoreReturnValue
  public boolean removeEdge(E edge) {

    Arrays.fill(array, ABSENT);
    return array;
  }

  /** Equivalent to {@code Arrays.copyOf(array, newSize)}, save that the new elements are ABSENT. */
  private static int[] expandAndFillWithAbsent(int[] array, int newSize) {
    int oldSize = array.length;
    int[] result = Arrays.copyOf(array, newSize);
    Arrays.fill(result, oldSize, newSize, ABSENT);
    return result;
  }

  @Override

  private final @Nullable V[][] array;

  private ArrayTable(Iterable<? extends R> rowKeys, Iterable<? extends C> columnKeys) {
    this.rowList = ImmutableList.copyOf(rowKeys);
    this.columnList = ImmutableList.copyOf(columnKeys);
    checkArgument(rowList.isEmpty() == columnList.isEmpty());

    /*
     * TODO(jlevy): Support only one of rowKey / columnKey being empty? If we

                this.rootArtifact = rootArtifact;
                this.root = root;
                this.dependencies = List.copyOf(requireNonNull(dependencies, "dependencies cannot be null"));
                this.managedDependencies =
                        List.copyOf(requireNonNull(managedDependencies, "managedDependencies cannot be null"));
                this.verbose = verbose;

            MavenProject child2Project = result2.getProject();

            // Capture repositories after building child2
            List<ArtifactRepository> repositoriesAfterChild2 = List.copyOf(sharedRequest.getRemoteRepositories());

            // Verify that child1 has its own repository
            boolean child1HasOwnRepo = child1Project.getRemoteArtifactRepositories().stream()

    ImmutableList.Builder<List<E>> axesBuilder = new ImmutableList.Builder<>(lists.size());
    for (List<? extends E> list : lists) {
      List<E> copy = ImmutableList.copyOf(list);
      if (copy.isEmpty()) {
        return ImmutableList.of();
      }
      axesBuilder.add(copy);
    }
    return new CartesianList<>(axesBuilder.build());
  }