@Nullable Integer expectedNodeCount = null;

  /**
   * Creates a new instance with the specified edge directionality.
   *
   * @param directed if true, creates an instance for graphs whose edges are each directed; if
   *     false, creates an instance for graphs whose edges are each undirected.
   */
  AbstractGraphBuilder(boolean directed) {
    this.directed = directed;
  }

  private GraphBuilder(boolean directed) {
    super(directed);
  }

  /** Returns a {@link GraphBuilder} for building directed graphs. */
  public static GraphBuilder<Object> directed() {
    return new GraphBuilder<>(true);
  }

  /** Returns a {@link GraphBuilder} for building undirected graphs. */
  public static GraphBuilder<Object> undirected() {
    return new GraphBuilder<>(false);
  }

  /**

    super(directed);
  }

  /** Returns a {@link ValueGraphBuilder} for building directed graphs. */
  public static ValueGraphBuilder<Object, Object> directed() {
    return new ValueGraphBuilder<>(true);
  }

  /** Returns a {@link ValueGraphBuilder} for building undirected graphs. */
  public static ValueGraphBuilder<Object, Object> undirected() {
    return new ValueGraphBuilder<>(false);
  }

  /**

 * map of edges to reference nodes. The reference node is defined to be the edge's source node on
 * directed graphs, and an arbitrary endpoint of the edge on undirected graphs.
 *
 * <p>Collection-returning accessors return unmodifiable views: the view returned will reflect
 * changes to the graph (if the graph is mutable) but may not be modified by the user.
 *

import static com.google.common.base.MoreObjects.firstNonNull;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.graph.GraphConstants.DEFAULT_NODE_COUNT;
import static com.google.common.graph.Graphs.checkNonNegative;

import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
import org.jspecify.annotations.Nullable;

/**

 * limitations under the License.
 */

package com.google.common.graph;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.graph.Graphs.checkNonNegative;

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import org.jspecify.annotations.Nullable;

/**

* ⬆ Bump actions/checkout from 4 to 5. PR [#13986](https://github.com/fastapi/fastapi/pull/13986) by [@dependabot[bot]](https://github.com/apps/dependabot).
* 🔧 Update Speakeasy sponsor graphic. PR [#13971](https://github.com/fastapi/fastapi/pull/13971) by [@chailandau](https://github.com/chailandau).

Implementation restriction: A compiler may restrict ImportPaths to
non-empty strings using only characters belonging to
<a href="https://www.unicode.org/versions/Unicode6.3.0/">Unicode's</a>
L, M, N, P, and S general categories (the Graphic characters without
spaces) and may also exclude the characters
<code>!"#$%&amp;'()*,:;&lt;=&gt;?[\]^`{|}</code>
and the Unicode replacement character U+FFFD.
</p>

<p>