/**
 * A {@link BiMap} backed by two hash tables. This implementation allows null keys and values. A
 * {@code HashBiMap} and its inverse are both serializable.
 *
 * <p>This implementation guarantees insertion-based iteration order of its keys.
 *
 * <p>See the Guava User Guide article on <a href=
 * "https://github.com/google/guava/wiki/NewCollectionTypesExplained#bimap">{@code BiMap} </a>.
 *
 * @author Louis Wasserman

    return Arrays.asList(
        new Object[][] {
          {false, false, ElementOrder.insertion(), ElementOrder.insertion()},
          {true, false, ElementOrder.insertion(), ElementOrder.insertion()},
          {false, false, naturalElementOrder, naturalElementOrder},
          {true, true, ElementOrder.insertion(), ElementOrder.insertion()},
        });
  }

  private final boolean allowsSelfLoops;

    return Arrays.asList(
        new Object[][] {
          {false, false, ElementOrder.insertion(), ElementOrder.insertion()},
          {true, false, ElementOrder.insertion(), ElementOrder.insertion()},
          {false, false, naturalElementOrder, naturalElementOrder},
          {true, true, ElementOrder.insertion(), ElementOrder.insertion()},
        });
  }

  private final boolean allowsSelfLoops;

    return Arrays.asList(
        new Object[][] {
          {false, false, ElementOrder.insertion(), ElementOrder.insertion()},
          {true, false, ElementOrder.insertion(), ElementOrder.insertion()},
          {false, false, naturalElementOrder, naturalElementOrder},
          {true, true, ElementOrder.insertion(), ElementOrder.insertion()},
        });
  }

  private final boolean allowsSelfLoops;

    return Arrays.asList(
        new Object[][] {
          {false, false, ElementOrder.insertion(), ElementOrder.insertion()},
          {true, false, ElementOrder.insertion(), ElementOrder.insertion()},
          {false, false, naturalElementOrder, naturalElementOrder},
          {true, true, ElementOrder.insertion(), ElementOrder.insertion()},
        });
  }

  private final boolean allowsSelfLoops;

    return Arrays.asList(
        new Object[][] {
          {false, false, ElementOrder.insertion(), ElementOrder.insertion()},
          {true, false, ElementOrder.insertion(), ElementOrder.insertion()},
          {false, false, naturalElementOrder, naturalElementOrder},
          {true, true, ElementOrder.insertion(), ElementOrder.insertion()},
        });
  }

  private final boolean allowsSelfLoops;

    return Arrays.asList(
        new Object[][] {
          {false, false, ElementOrder.insertion(), ElementOrder.insertion()},
          {true, false, ElementOrder.insertion(), ElementOrder.insertion()},
          {false, false, naturalElementOrder, naturalElementOrder},
          {true, true, ElementOrder.insertion(), ElementOrder.insertion()},
        });
  }

  private final boolean allowsSelfLoops;

 * terms</a>):
 *
 * <ul>
 *   <li>directed graphs
 *   <li>undirected graphs
 *   <li>graphs that do/don't allow parallel edges
 *   <li>graphs that do/don't allow self-loops
 *   <li>graphs whose nodes/edges are insertion-ordered, sorted, or unordered
 *   <li>graphs whose edges are <a
 *       href="https://github.com/google/guava/wiki/GraphsExplained#uniqueness">unique</a> objects
 * </ul>
 *
 * <h3>Building a {@code Network}</h3>
 *

            ImmutableCollection.Builder.expandedCapacity(dedupedElements.length, minCapacity);
        dedupedElements = Arrays.copyOf(dedupedElements, newCapacity);
      }
    }

    /** Adds e to the insertion-order array of deduplicated elements. Calls ensureCapacity. */
    final void addDedupedElement(E e) {
      ensureCapacity(distinct + 1);
      dedupedElements[distinct++] = e;
    }

    /**

 *
 * @author James Sexton
 */
abstract class AbstractGraphBuilder<N> {
  final boolean directed;
  boolean allowsSelfLoops = false;
  ElementOrder<N> nodeOrder = ElementOrder.insertion();
  ElementOrder<N> incidentEdgeOrder = ElementOrder.unordered();

  @Nullable Integer expectedNodeCount = null;

  /**
   * Creates a new instance with the specified edge directionality.
   *