return new NetworkBuilder<>(false);
  }

  /**
   * Returns a {@link NetworkBuilder} initialized with all properties queryable from {@code
   * network}.
   *
   * <p>The "queryable" properties are those that are exposed through the {@link Network} interface,
   * such as {@link Network#isDirected()}. Other properties, such as {@link
   * #expectedNodeCount(int)}, are not set in the new builder.
   */

    return new ValueGraphBuilder<>(false);
  }

  /**
   * Returns a {@link ValueGraphBuilder} initialized with all properties queryable from {@code
   * graph}.
   *
   * <p>The "queryable" properties are those that are exposed through the {@link ValueGraph}
   * interface, such as {@link ValueGraph#isDirected()}. Other properties, such as {@link
   * #expectedNodeCount(int)}, are not set in the new builder.
   */

   * Returns the result of applying this predicate to {@code input} (Java 8+ users, see notes in the
   * class documentation above). This method is <i>generally expected</i>, but not absolutely
   * required, to have the following properties:
   *
   * <ul>
   *   <li>Its execution does not cause any observable side effects.
   *   <li>The computation is <i>consistent with equals</i>; that is, {@link Objects#equal

final class StandardMutableValueGraph<N, V> extends StandardValueGraph<N, V>
    implements MutableValueGraph<N, V> {

  private final ElementOrder<N> incidentEdgeOrder;

  /** Constructs a mutable graph with the properties specified in {@code builder}. */
  StandardMutableValueGraph(AbstractGraphBuilder<? super N> builder) {
    super(builder);
    incidentEdgeOrder = builder.incidentEdgeOrder.cast();
  }

  @Override

    g2.addEdge(N1, N2, E13);
    g2.addEdge(N1, N3, E12);

    assertThat(network).isNotEqualTo(g2);
  }

  // Node/edge sets and node/edge connections are the same, but network properties differ.
  // (In this case the networks are considered equivalent; the property differences are irrelevant.)
  @Test
  public void equivalent_propertiesDiffer() {
    network.addEdge(N1, N2, E12);

   *   <li>Unusual environments like GWT may have their own special handling of system properties.
   * </ul>
   *
   * <p>Note that {@code StandardSystemProperty} does not provide constants for more recently added
   * properties, including:
   *
   * <ul>
   *   <li>{@code java.vendor.version} (added in Java 11, listed as optional as of Java 13)

  public void testFromPropertiesNullKey() {
    Properties properties =
        new Properties() {
          @Override
          public Enumeration<?> propertyNames() {
            return Iterators.asEnumeration(Arrays.asList(null, "first", "second").iterator());
          }
        };
    properties.setProperty("first", "true");
    properties.setProperty("second", "null");

    try {

  public void testFromPropertiesNullKey() {
    Properties properties =
        new Properties() {
          @Override
          public Enumeration<?> propertyNames() {
            return Iterators.asEnumeration(Arrays.asList(null, "first", "second").iterator());
          }
        };
    properties.setProperty("first", "true");
    properties.setProperty("second", "null");

    try {

     *
     * <p>After calling this method, you can keep adding more properties to later call toString()
     * again and get a more complete representation of the same object; but properties cannot be
     * removed, so this only allows limited reuse of the helper instance. The helper allows
     * duplication of properties (multiple name/value pairs with the same name can be added).
     */
    @Override

 * be used to decide whether to apply a test to a given class-under-test.
 *
 * <p>This is needed because annotations can't implement interfaces, which is also why reflection is
 * used to extract values from the properties of the various annotations.
 *
 * @author George van den Driessche
 */
@Target(value = {java.lang.annotation.ElementType.ANNOTATION_TYPE})
@Retention(value = RetentionPolicy.RUNTIME)
@Documented
@GwtCompatible