// here to provide error messages.
  // TODO(user): Some Strings used in the subclasses can be added as static Strings
  // here too.
  static final String ERROR_MODIFIABLE_SET = "Set returned is unexpectedly modifiable";
  static final String ERROR_SELF_LOOP = "self-loops are not allowed";
  static final String ERROR_ADDED_SELF_LOOP = "Should not be allowed to add a self-loop edge.";

  static final String ERROR_REUSE_EDGE = "it cannot be reused to connect";
  static final String ERROR_MODIFIABLE_COLLECTION =
      "Collection returned is unexpectedly modifiable";
  static final String ERROR_SELF_LOOP = "self-loops are not allowed";
  static final String ERROR_EDGE_NOT_IN_GRAPH =
      "Should not be allowed to pass an edge that is not an element of the graph.";

 * through the iterator's methods, the results of the iteration are undefined.
 *
 * <p>Keys and values may be null. All optional multimap methods are supported, and all returned
 * views are modifiable.
 *
 * <p>This class is not threadsafe when any concurrent operations update the multimap. Concurrent
 * read operations will work correctly. To allow concurrent update operations, wrap your multimap

  private <T extends Comparable<T>> void runIterator(final List<T> values, int steps)
      throws Exception {
    IteratorTester<T> tester =
        new IteratorTester<T>(
            steps,
            IteratorFeature.MODIFIABLE,
            Lists.newLinkedList(values),
            IteratorTester.KnownOrder.UNKNOWN_ORDER) {
          private @Nullable MinMaxPriorityQueue<T> mmHeap;

          @Override

  private <T extends Comparable<T>> void runIterator(final List<T> values, int steps)
      throws Exception {
    IteratorTester<T> tester =
        new IteratorTester<T>(
            steps,
            IteratorFeature.MODIFIABLE,
            Lists.newLinkedList(values),
            IteratorTester.KnownOrder.UNKNOWN_ORDER) {
          private @Nullable MinMaxPriorityQueue<T> mmHeap;

          @Override

    long addressAsLong = 0;
    if (hasEmbeddedIPv4ClientAddress(ip6)) {
      addressAsLong = getEmbeddedIPv4ClientAddress(ip6).hashCode();
    } else {
      // Just extract the high 64 bits (assuming the rest is user-modifiable).
      addressAsLong = ByteBuffer.wrap(ip6.getAddress(), 0, 8).getLong();
    }

    // Many strategies for hashing are possible. This might suffice for now.

    long addressAsLong = 0;
    if (hasEmbeddedIPv4ClientAddress(ip6)) {
      addressAsLong = getEmbeddedIPv4ClientAddress(ip6).hashCode();
    } else {
      // Just extract the high 64 bits (assuming the rest is user-modifiable).
      addressAsLong = ByteBuffer.wrap(ip6.getAddress(), 0, 8).getLong();
    }

    // Many strategies for hashing are possible. This might suffice for now.