* A class to allow {@link Graph} implementations to be backed by a {@link BaseGraph}. This is not
 * currently planned to be released as a general-purpose forwarding class.
 *
 * @author James Sexton
 */
abstract class ForwardingGraph<N> extends AbstractGraph<N> {

  abstract BaseGraph<N> delegate();

  @Override
  public Set<N> nodes() {
    return delegate().nodes();
  }

  /**

 * A class to allow {@link Graph} implementations to be backed by a {@link BaseGraph}. This is not
 * currently planned to be released as a general-purpose forwarding class.
 *
 * @author James Sexton
 */
abstract class ForwardingGraph<N> extends AbstractGraph<N> {

  abstract BaseGraph<N> delegate();

  @Override
  public Set<N> nodes() {
    return delegate().nodes();
  }

  /**

 * @author Joshua O'Madadhain
 * @author Omar Darwish
 * @author Jens Nyman
 * @param <N> Node parameter type
 * @since 20.0
 */
@Beta
@Immutable(containerOf = {"N"})
public class ImmutableGraph<N> extends ForwardingGraph<N> {
  @SuppressWarnings("Immutable") // The backing graph must be immutable.
  private final BaseGraph<N> backingGraph;

  ImmutableGraph(BaseGraph<N> backingGraph) {
    this.backingGraph = backingGraph;
  }