* @param <E> Edge parameter type
 */
@ElementTypesAreNonnullByDefault
abstract class AbstractUndirectedNetworkConnections<N, E> implements NetworkConnections<N, E> {
  /** Keys are edges incident to the origin node, values are the node at the other end. */
  final Map<E, N> incidentEdgeMap;

  AbstractUndirectedNetworkConnections(Map<E, N> incidentEdgeMap) {
    this.incidentEdgeMap = checkNotNull(incidentEdgeMap);
  }

    private final Object successorValue;

    PredAndSucc(Object successorValue) {
      this.successorValue = successorValue;
    }
  }

  /**
   * A value class representing single connection between the origin node and another node.
   *
   * <p>There can be two types of connections (predecessor and successor), which is represented by
   * the two implementations.
   */
  private abstract static class NodeConnection<N> {

    public static final String SAME_ORIGIN = "same-origin";
    public static final String ORIGIN = "origin";
    public static final String STRICT_ORIGIN = "strict-origin";
    public static final String ORIGIN_WHEN_CROSS_ORIGIN = "origin-when-cross-origin";
    public static final String STRICT_ORIGIN_WHEN_CROSS_ORIGIN = "strict-origin-when-cross-origin";
    public static final String UNSAFE_URL = "unsafe-url";
  }

  static <E> Set<E> reserializeAndAssertLenient(Set<E> original) {
    Set<E> copy = reserialize(original);
    assertEquals(original, copy);
    assertTrue(copy instanceof ImmutableSet);
    return copy;
  }

  @CanIgnoreReturnValue
  @GwtIncompatible // SerializableTester
  static <E> Multiset<E> reserializeAndAssertLenient(Multiset<E> original) {
    Multiset<E> copy = reserialize(original);
    assertEquals(original, copy);

    assertSame(Ordering.natural(), copy.comparator());
  }

  public void testCopyOf() {
    Map<String, Integer> original = new LinkedHashMap<>();
    original.put("one", 1);
    original.put("two", 2);
    original.put("three", 3);

    ImmutableSortedMap<String, Integer> copy = ImmutableSortedMap.copyOf(original);
    assertMapEquals(copy, "one", 1, "three", 3, "two", 2);
    assertSame(copy, ImmutableSortedMap.copyOf(copy));

  @CollectionSize.Require(absent = ZERO)
  @MapFeature.Require(ALLOWS_NULL_KEYS)
  public void testEqualsMultimapWithNullKey() {
    Multimap<K, V> original = multimap();
    initMultimapWithNullKey();
    Multimap<K, V> withNull = multimap();
    new EqualsTester()
        .addEqualityGroup(original)
        .addEqualityGroup(
            withNull, getSubjectGenerator().create((Object[]) createArrayWithNullKey()))
        .testEquals();
  }

  public TablesTransposeColumnTest() {
    super(false, true, true, true, true);
  }

  @Override
  Table<String, Character, Integer> makeTable() {
    Table<Character, String, Integer> original = TreeBasedTable.create();
    return Tables.transpose(original);
  }

    } catch (IllegalArgumentException expected) {
    }
  }

  public void testCreateCopy() {
    Table<String, Integer, Character> original =
        create("foo", 1, 'a', "bar", 1, 'b', "foo", 3, 'c');
    Table<String, Integer, Character> copy = HashBasedTable.create(original);
    assertEquals(original, copy);
    assertEquals((Character) 'a', copy.get("foo", 1));
  }

  @J2ktIncompatible
  @GwtIncompatible // SerializableTester

    super(false, false, false, false);
  }

  @Override
  Table<Integer, String, Character> makeTable() {
    RowSortedTable<Integer, String, Character> original = TreeBasedTable.create();
    return Tables.unmodifiableRowSortedTable(original);
  }

  @Override
  protected Map<String, Map<Integer, Character>> makePopulatedMap() {
    RowSortedTable<Integer, String, Character> table = TreeBasedTable.create();

    super(false, false, false, false);
  }

  @Override
  Table<Integer, String, Character> makeTable() {
    Table<Integer, String, Character> original = HashBasedTable.create();
    return Tables.unmodifiableTable(original);
  }

  @Override
  protected Map<String, Map<Integer, Character>> makePopulatedMap() {
    Table<Integer, String, Character> table = HashBasedTable.create();