/**
   * The "base64" base encoding specified by <a
   * href="http://tools.ietf.org/html/rfc4648#section-4">RFC 4648 section 4</a>, Base 64 Encoding.
   * (This is the same as the base 64 encoding from <a
   * href="http://tools.ietf.org/html/rfc3548#section-3">RFC 3548</a>.)
   *
   * <p>The character {@code '='} is used for padding, but can be {@linkplain #omitPadding()

/** `100 Continue` (HTTP/1.1 - RFC 7231)  */
const val HTTP_CONTINUE = 100

/** `101 Switching Protocols` (HTTP/1.1 - RFC 9110)  */
const val HTTP_SWITCHING_PROTOCOLS = 101

/** `102 Processing` (WebDAV - RFC 2518)  */
const val HTTP_PROCESSING = 102

/** `103 Early Hints (Early Hints - RFC 8297)` */
const val HTTP_EARLY_HINTS = 103

/** `307 Temporary Redirect` (HTTP/1.1 - RFC 7231)  */
const val HTTP_TEMP_REDIRECT = 307

OkHttp follows modern HTTP specifications such as

* HTTP Semantics - [RFC 9110](https://datatracker.ietf.org/doc/html/rfc9110)
* HTTP Caching- [RFC 9111](https://datatracker.ietf.org/doc/html/rfc9111)
* HTTP/1.1 - [RFC 9112](https://datatracker.ietf.org/doc/html/rfc9112)
* HTTP/2 - [RFC 9113](https://datatracker.ietf.org/doc/html/rfc9113)
* Websockets - [RFC 6455](https://datatracker.ietf.org/doc/html/rfc6455)

Починаючи з версії FastAPI `0.122.0`, вони використовують більш доречний HTTP код статусу `401 Unauthorized` і повертають змістовний заголовок `WWW-Authenticate` у відповіді, відповідно до специфікацій HTTP, [RFC 7235](https://datatracker.ietf.org/doc/html/rfc7235#section-3.1), [RFC 9110](https://datatracker.ietf.org/doc/html/rfc9110#name-401-unauthorized).

  public static final MediaType I_CALENDAR_UTF_8 = createConstantUtf8(TEXT_TYPE, "calendar");

  /**
   * As described in <a href="https://www.rfc-editor.org/rfc/rfc7763.html">RFC 7763</a>, this
   * constant ({@code text/markdown}) is used for Markdown documents.
   *
   * @since 33.3.0
   */
  public static final MediaType MD_UTF_8 = createConstantUtf8(TEXT_TYPE, "markdown");

   * label. See <a href="http://www.ietf.org/rfc/rfc2181.txt">RFC 2181</a> part 11.
   */
  private static final int MAX_LENGTH = 253;

  /**
   * Maximum size of a single part of a domain name. See <a
   * href="http://www.ietf.org/rfc/rfc2181.txt">RFC 2181</a> part 11.
   */
  private static final int MAX_DOMAIN_PART_LENGTH = 63;

Начиная с версии FastAPI `0.122.0`, используется более подходящий HTTP статус-код `401 Unauthorized`, и в ответе возвращается имеющий смысл HTTP-заголовок `WWW-Authenticate` в соответствии со спецификациями HTTP, [RFC 7235](https://datatracker.ietf.org/doc/html/rfc7235#section-3.1), [RFC 9110](https://datatracker.ietf.org/doc/html/rfc9110#name-401-unauthorized).

`0.122.0` sürümünden itibaren ise daha uygun olan HTTP durum kodu `401 Unauthorized` kullanılmakta ve HTTP spesifikasyonlarına uygun olarak response içinde anlamlı bir `WWW-Authenticate` header'ı döndürülmektedir, [RFC 7235](https://datatracker.ietf.org/doc/html/rfc7235#section-3.1), [RFC 9110](https://datatracker.ietf.org/doc/html/rfc9110#name-401-unauthorized).

Ancak herhangi bir nedenle client'larınız eski davranışa bağlıysa, security class'larınızda `make_not_authenticated_error` metodunu...

Ab FastAPI-Version `0.122.0` verwenden sie den passenderen HTTP-Statuscode `401 Unauthorized` und geben in der Response einen sinnvollen `WWW-Authenticate`-Header zurück, gemäß den HTTP-Spezifikationen, [RFC 7235](https://datatracker.ietf.org/doc/html/rfc7235#section-3.1), [RFC 9110](https://datatracker.ietf.org/doc/html/rfc9110#name-401-unauthorized).

在 FastAPI `0.122.0` 版本之前，当内置的安全工具在认证失败后向客户端返回错误时，会使用 HTTP 状态码 `403 Forbidden`。

从 FastAPI `0.122.0` 版本开始，它们改用更合适的 HTTP 状态码 `401 Unauthorized`，并在响应中返回合理的 `WWW-Authenticate` 头，遵循 HTTP 规范，[RFC 7235](https://datatracker.ietf.org/doc/html/rfc7235#section-3.1)、[RFC 9110](https://datatracker.ietf.org/doc/html/rfc9110#name-401-unauthorized)。

但如果由于某些原因你的客户端依赖旧行为，你可以在你的安全类中重写方法 `make_not_authenticated_error` 来回退到旧行为。