Das ist nützlich für Vorgänge, die nach einem <abbr title="Request – Anfrage: Daten, die der Client zum Server sendet">Request</abbr> ausgeführt werden müssen, bei denen der Client jedoch nicht unbedingt auf den Abschluss des Vorgangs warten muss, bevor er die Response erhält.

public final class PrintEvents {
  private final OkHttpClient client = new OkHttpClient.Builder()
      .eventListenerFactory(PrintingEventListener.FACTORY)
      .build();

  public void run() throws Exception {
    Request washingtonPostRequest = new Request.Builder()
        .url("https://www.washingtonpost.com/")
        .build();
    client.newCall(washingtonPostRequest).enqueue(new Callback() {

You can use Pydantic's model configuration to `forbid` any `extra` fields:

{* ../../docs_src/header_param_models/tutorial002_an_py310.py hl[10] *}

If a client tries to send some **extra headers**, they will receive an **error** response.

For example, if the client tries to send a `tool` header with a value of `plumbus`, they will receive an **error** response telling them that the header parameter `tool` is not allowed:

```json
{

public static final String USE_MULTI_CHANNEL = "jcifs.smb.client.useMultiChannel";
public static final String MAX_CHANNELS = "jcifs.smb.client.maxChannels";
public static final String CHANNEL_BINDING_POLICY = "jcifs.smb.client.channelBindingPolicy";
public static final String LOAD_BALANCING_STRATEGY = "jcifs.smb.client.loadBalancingStrategy";
public static final String CHANNEL_HEALTH_CHECK_INTERVAL = "jcifs.smb.client.channelHealthCheckInterval";

/* jcifs smb client library in Java
 * Copyright (C) 2000  "Michael B. Allen" <jcifs at samba dot org>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,

 *   <li>Carries contextual data describing the current request or operation</li>
 *   <li>Supports both internal session operations and client-provided trace information</li>
 * </ul>
 *
 * <p>For internal session operations, the trace typically contains {@code *Request} objects
 * that represent the current processing state. Client code can also create traces with
 * application-specific data to provide context when invoking session methods.</p>
 *

  private final OkHttpClient client = new OkHttpClient();

  public void run() throws Exception {
    Request request = new Request.Builder()
        .url("http://httpbin.org/delay/2") // This URL is served with a 2 second delay.
        .build();

    final long startNanos = System.nanoTime();
    final Call call = client.newCall(request);

    // Schedule a job to cancel the call in 1 second.

  }

  public static void main(String... args) throws Exception {
    OkHttpClient client = new OkHttpClient();

    // Create request for remote resource.
    Request request = new Request.Builder()
        .url(ENDPOINT)
        .build();

    // Execute the request and retrieve the response.
    try (Response response = client.newCall(request).execute()) {
      // Deserialize HTTP response to concrete type.

	// OpMuxConnectError is an  error while connecting a mux.
	OpMuxConnectError

	// OpDisconnectClientMux instructs a client to disconnect a mux
	OpDisconnectClientMux

	// OpDisconnectServerMux instructs a server to disconnect (cancel) a server mux
	OpDisconnectServerMux

	// OpMuxClientMsg contains a message to a client Mux
	OpMuxClientMsg

	// OpMuxServerMsg contains a message to a server Mux
	OpMuxServerMsg

    The HTTP authorization header value is split by the first space.

    The first part is the `scheme`, the second part is the `credentials`.

    For example, in an HTTP Bearer token scheme, the client will send a header
    like:

    ```
    Authorization: Bearer deadbeef12346
    ```

    In this case:

    * `scheme` will have the value `"Bearer"`