* and the implementation should respond with a new request that sets the "Authorization" header.
 *
 * ```java
 * if (response.request().header("Authorization") != null) {
 *   return null; // Give up, we've already failed to authenticate.
 * }
 *
 * String credential = Credentials.basic(...)
 * return response.request().newBuilder()
 *     .header("Authorization", credential)
 *     .build();
 * ```
 *

}

// ClusterRole is a cluster level, logical grouping of PolicyRules that can be referenced as a unit by a RoleBinding or ClusterRoleBinding.
// Deprecated in v1.17 in favor of rbac.authorization.k8s.io/v1 ClusterRole, and will no longer be served in v1.22.
message ClusterRole {
  // Standard object's metadata.
  // +optional
  optional k8s.io.apimachinery.pkg.apis.meta.v1.ObjectMeta metadata = 1;

}

// ClusterRole is a cluster level, logical grouping of PolicyRules that can be referenced as a unit by a RoleBinding or ClusterRoleBinding.
// Deprecated in v1.17 in favor of rbac.authorization.k8s.io/v1 ClusterRole, and will no longer be served in v1.22.
message ClusterRole {
  // Standard object's metadata.
  // +optional
  optional k8s.io.apimachinery.pkg.apis.meta.v1.ObjectMeta metadata = 1;

syntax = "proto2";

package k8s.io.api.authorization.v1beta1;

import "k8s.io/apimachinery/pkg/apis/meta/v1/generated.proto";
import "k8s.io/apimachinery/pkg/runtime/generated.proto";
import "k8s.io/apimachinery/pkg/runtime/schema/generated.proto";

// Package-wide variables from generator "generated".
option go_package = "k8s.io/api/authorization/v1beta1";

// ExtraValue masks the value so protobuf can generate

        .add("content-length", "99")
        .add("authorization", "peanutbutter")
        .add("proxy-authorization", "chocolate")
        .add("cookie", "drink=coffee")
        .add("set-cookie", "accessory=sugar")
        .add("user-agent", "OkHttp")
        .build()
    assertThat(headers.toString()).isEqualTo(
      """
      |content-length: 99
      |authorization: ██
      |proxy-authorization: ██
      |cookie: ██

syntax = "proto2";

package k8s.io.api.authorization.v1;

import "k8s.io/apimachinery/pkg/apis/meta/v1/generated.proto";
import "k8s.io/apimachinery/pkg/runtime/generated.proto";
import "k8s.io/apimachinery/pkg/runtime/schema/generated.proto";

// Package-wide variables from generator "generated".
option go_package = "k8s.io/api/authorization/v1";

// ExtraValue masks the value so protobuf can generate

          @Throws(IOException::class)
          override fun authenticate(
            route: Route?,
            response: Response,
          ): Request? {
            if (response.request.header("Authorization") != null) {
              return null // Give up, we've already attempted to authenticate.
            }

            println("Authenticating for response: $response")

    * Но для этого необходима аутентификация для конкретной конечной точки.
    * Поэтому для аутентификации в нашем API он посылает заголовок `Authorization` со значением `Bearer` плюс сам токен.
    * Если токен содержит `foobar`, то содержание заголовка `Authorization` будет таким: `Bearer foobar`.

## Класс `OAuth2PasswordBearer` в **FastAPI**

    - 这样一来，就算令牌被人窃取，风险也较低。因为它与永久密钥不同，**在绝大多数情况下**不会长期有效
- 前端临时将令牌存储在某个位置
- 用户点击前端，前往前端应用的其它部件
- 前端需要从 API 中提取更多数据：
    - 为指定的端点（Endpoint）进行身份验证
    - 因此，用 API 验证身份时，要发送值为 `Bearer` + 令牌的请求头 `Authorization`
    - 假如令牌为 `foobar`，`Authorization` 请求头就是： `Bearer foobar`

## **FastAPI** 的 `OAuth2PasswordBearer`

**FastAPI** 提供了不同抽象级别的安全工具。

本例使用 **OAuth2** 的 **Password** 流以及 **Bearer** 令牌（`Token`）。为此要使用 `OAuth2PasswordBearer` 类。

      "Successful auth!",
    )

    // No authorization header for the first request...
    var request = server.takeRequest()
    assertThat(request.headers["Authorization"]).isNull()

    // ...but the three requests that follow include an authorization header.
    for (i in 0..2) {
      request = server.takeRequest()