}

    /**
     * Use an XPath string to select a single node.
     *
     * @param contextNode The node to start searching from.
     * @param expression A valid XPath string.
     * @return The first node found that matches the XPath, or null.
     *
     * @throws XPathExpressionException
     */
    public Node selectSingleNode(final Node contextNode, final String expression) throws XPathExpressionException {

Instead of configuring an external KMS you can start with a single key by
setting the env. variable `MINIO_KMS_SECRET_KEY`. It expects the following
format:

```sh
MINIO_KMS_SECRET_KEY=<key-name>:<base64-value>
```

First generate a 256 bit random key via:

```sh
$ cat /dev/urandom | head -c 32 | base64 -
OSMM+vkKUTCvQs9YL/CVMIMt43HFhkUpqJxTmGl6rYw=
```

Now, you can set `MINIO_KMS_SECRET_KEY` like this:

```sh

                    const char* mutation_type) {
  // If any session has already run this node_id, mark this session as
  // unrunnable.
  for (auto it : graph->sessions) {
    mutex_lock session_lock(it.first->mu);
    if (it.first->last_num_graph_nodes > op.node.id()) {
      it.second = strings::StrCat(
          "Operation '", op.node.DebugString(), "' was changed by ",
          mutation_type,

# Cookie Parameters

You can define Cookie parameters the same way you define `Query` and `Path` parameters.

## Import `Cookie`

First import `Cookie`:

//// tab | Python 3.10+

```Python hl_lines="3"
{!> ../../docs_src/cookie_params/tutorial001_an_py310.py!}
```

////

//// tab | Python 3.9+

```Python hl_lines="3"
{!> ../../docs_src/cookie_params/tutorial001_an_py39.py!}
```

////

    public WithPublicConstructorAndConstant() {}
  }

  private static class WithPublicConstants {
    public static final WithPublicConstants FIRST = new WithPublicConstants();

    // To test that we pick the first constant alphabetically
    @SuppressWarnings("unused")
    public static final WithPublicConstants SECOND = new WithPublicConstants();
  }

  private static File file(String first, String... more) {
    return file(new File(first), more);
  }

  /** Returns a {@code File} object for the given path parts. */
  private static File file(File first, String... more) {
    // not very efficient, but should definitely be correct
    File file = first;
    for (String name : more) {
      file = new File(file, name);
    }

This document provides an overview of the architecture and design decisions around Ztunnel, the node-proxy component in ambient mode.

## Background and motivation

Motivations to implement ztunnel generally came from two areas.

First, and most importantly, it serves as a means to implement the real goal: waypoints.
For various reasons outside the scope of this document, there is a desire to move from a sidecar based architecture to a "remote proxy" architecture.

    val startsFirst = buildRequestThread(firstRequest, firstResponseCode)
    startsFirst.start()
    val endsFirst = buildRequestThread(secondRequest, secondResponseCode)
    endsFirst.start()
    endsFirst.join()
    // First response is still waiting.
    assertThat(firstResponseCode.get()).isEqualTo(0)
    // Second response is done.
    assertThat(secondResponseCode.get()).isEqualTo(200)
    latch.countDown()
    startsFirst.join()

import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A {@code Multiset} implementation with predictable iteration order. Its iterator orders elements
 * according to when the first occurrence of the element was added. When the multiset contains
 * multiple instances of an element, those instances are consecutive in the iteration order. If all

    assertThat(fooReference1).isNotSameInstanceAs(fooReference2);

    assertThat(mapCache.put(fooReference1, "bar")).isNull();
    assertThat(mapCache.get(fooReference1)).isEqualTo("bar"); // ensure first reference is cached
    assertThat(mapCache.remove(fooReference2)).isEqualTo("bar");
    assertThat(mapCache.get(fooReference1)).isNull();
  }