connections.removePredecessor(node);
        --edgeCount;
      }
    }

    for (N successor : ImmutableList.copyOf(connections.successors())) {
      // requireNonNull is safe because the node is a successor.
      requireNonNull(nodeConnections.getWithoutCaching(successor)).removePredecessor(node);
      requireNonNull(connections.removeSuccessor(successor));
      --edgeCount;
    }

        (nodeConnections instanceof TreeMap)
            ? new MapRetrievalCache<>(nodeConnections)
            : new MapIteratorCache<>(nodeConnections);
    this.edgeCount = checkNonNegative(edgeCount);
  }

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

  @Override
  public boolean isDirected() {
    return isDirected;
  }

  @Override

    return delegate().nodes();
  }

  /**
   * Defer to {@link AbstractValueGraph#edges()} (based on {@link #successors(Object)}) for full
   * edges() implementation.
   */
  @Override
  protected long edgeCount() {
    return delegate().edges().size();
  }

  @Override
  public boolean isDirected() {
    return delegate().isDirected();
  }

  @Override
  public boolean allowsSelfLoops() {

    return delegate().nodes();
  }

  /**
   * Defer to {@link AbstractGraph#edges()} (based on {@link #successors(Object)}) for full edges()
   * implementation.
   */
  @Override
  protected long edgeCount() {
    return delegate().edges().size();
  }

  @Override
  public boolean isDirected() {
    return delegate().isDirected();
  }

  @Override
  public boolean allowsSelfLoops() {