* and updates {@link #successorIterator} to iterate through the successors of {@link #node}.
   */
  final boolean advance() {
    checkState(!successorIterator.hasNext());
    if (!nodeIterator.hasNext()) {
      return false;
    }
    node = nodeIterator.next();
    successorIterator = graph.successors(node).iterator();
    return true;
  }

  /**

      }

      @Override
      public Set<N> predecessors(N node) {
        return AbstractValueGraph.this.predecessors(node);
      }

      @Override
      public Set<N> successors(N node) {
        return AbstractValueGraph.this.successors(node);
      }

      @Override
      public int degree(N node) {
        return AbstractValueGraph.this.degree(node);
      }

      @Override

        return sb.toString();
    }

    // ===================================================================================
    //                                                                            Accessor
    //                                                                            ========
    public String getCreatedBy() {
        checkSpecifiedProperty("createdBy");
        return convertEmptyToNull(createdBy);

        return sb.toString();
    }

    // ===================================================================================
    //                                                                            Accessor
    //                                                                            ========
    public Long getCreatedTime() {
        checkSpecifiedProperty("createdTime");
        return createdTime;
    }

        return sb.toString();
    }

    // ===================================================================================
    //                                                                            Accessor
    //                                                                            ========
    public String getCrawlingInfoId() {
        checkSpecifiedProperty("crawlingInfoId");

        return sb.toString();
    }

    // ===================================================================================
    //                                                                            Accessor
    //                                                                            ========
    public String getCreatedBy() {
        checkSpecifiedProperty("createdBy");
        return convertEmptyToNull(createdBy);

        return sb.toString();
    }

    // ===================================================================================
    //                                                                            Accessor
    //                                                                            ========
    public String getName() {
        checkSpecifiedProperty("name");
        return convertEmptyToNull(name);
    }

@SuppressWarnings("JUnit4ClassUsedInJUnit3")
@NullMarked
public abstract class AbstractCollectionTester<E extends @Nullable Object>
    extends AbstractContainerTester<Collection<E>, E> {

  // TODO: replace this with an accessor.
  protected Collection<E> collection;

  @Override
  protected Collection<E> actualContents() {
    return collection;
  }

  // TODO: dispose of this once collection is encapsulated.
  @Override

@SuppressWarnings("JUnit4ClassUsedInJUnit3")
@NullMarked
public abstract class AbstractCollectionTester<E extends @Nullable Object>
    extends AbstractContainerTester<Collection<E>, E> {

  // TODO: replace this with an accessor.
  protected Collection<E> collection;

  @Override
  protected Collection<E> actualContents() {
    return collection;
  }

  // TODO: dispose of this once collection is encapsulated.
  @Override

    return delegate().adjacentNodes(node);
  }

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

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

  @Override
  public Set<E> incidentEdges(N node) {
    return delegate().incidentEdges(node);
  }

  @Override
  public Set<E> inEdges(N node) {