}

  /**
   * Returns an immutable multimap containing the specified entries. The returned multimap iterates
   * over keys in the order they were first encountered in the input, and the values for each key
   * are iterated in the order they were encountered.
   *
   * @throws NullPointerException if any key, value, or entry is null
   * @since 19.0
   */

   * For example, two networks may be considered equal even if one allows parallel edges and the
   * other doesn't. Additionally, the order in which nodes or edges are added to the network, and
   * the order in which they are iterated over, are irrelevant.
   *
   * <p>A reference implementation of this is provided by {@link AbstractNetwork#equals(Object)}.
   */
  @Override

    return new ImmutableIntArray(new int[] {e0});
  }

  /** Returns an immutable array containing the given values, in order. */
  public static ImmutableIntArray of(int e0, int e1) {
    return new ImmutableIntArray(new int[] {e0, e1});
  }

  /** Returns an immutable array containing the given values, in order. */
  public static ImmutableIntArray of(int e0, int e1, int e2) {
    return new ImmutableIntArray(new int[] {e0, e1, e2});

This offered performance benefits that were too large to leave on the table, as well as opportunities to tune to our specific needs.

## Configuration protocol

Ztunnel, of course, needs to be dynamically configured in order to make decisions on how it should handle traffic.
For this purpose, we chose to use xDS transport protocol due to our expertise and existing infrastructure, and because the protocol is well suited to our needs.

    // re-order
    getAll(cache, asList(0, 1, 2));
    CacheTesting.drainRecencyQueues(cache);
    assertThat(keySet).containsExactly(3, 4, 5, 6, 7, 8, 9, 0, 1, 2);

    // evict 3, 4, 5
    getAll(cache, asList(10, 11, 12));
    CacheTesting.drainRecencyQueues(cache);
    assertThat(keySet).containsExactly(6, 7, 8, 9, 0, 1, 2, 10, 11, 12);

    // re-order
    getAll(cache, asList(6, 7, 8));

   * For example, two graphs may be considered equal even if one allows self-loops and the other
   * doesn't. Additionally, the order in which nodes or edges are added to the graph, and the order
   * in which they are iterated over, are irrelevant.
   *
   * <p>A reference implementation of this is provided by {@link AbstractValueGraph#equals(Object)}.
   */
  @Override

1. Config ingestion (inputs to the system)
1. Config translation
1. Config serving (XDS)

### Config Ingestion

Istio reads from over 20 different resources types, and aggregates them together to build the proxy configuration. These resources can be sourced from Kubernetes (via watches), files, or over xDS; Kubernetes is by far the most common usage, though.

Primarily for historical reasons, ingestion is split into a few components.

   * For example, two graphs may be considered equal even if one allows self-loops and the other
   * doesn't. Additionally, the order in which nodes or edges are added to the graph, and the order
   * in which they are iterated over, are irrelevant.
   *
   * <p>A reference implementation of this is provided by {@link AbstractGraph#equals(Object)}.
   */
  @Override

   * For example, two graphs may be considered equal even if one allows self-loops and the other
   * doesn't. Additionally, the order in which nodes or edges are added to the graph, and the order
   * in which they are iterated over, are irrelevant.
   *
   * <p>A reference implementation of this is provided by {@link AbstractGraph#equals(Object)}.
   */
  @Override

  }

  /** Returns an immutable array containing the given values, in order. */
  public static ImmutableDoubleArray of(double e0, double e1) {
    return new ImmutableDoubleArray(new double[] {e0, e1});
  }

  /** Returns an immutable array containing the given values, in order. */
  public static ImmutableDoubleArray of(double e0, double e1, double e2) {