@SuppressWarnings("unchecked")
      Map<String, String> proxy =
          Reflection.newProxy(Map.class, new CheckSetUpInvocationHandler(map, setUpRan));
      return proxy;
    }
  }

  /**
   * Intercepts calls to a {@code Map} to check that {@code setUpRan} is true when they happen. Then
   * forwards the calls to the underlying {@code Map}.
   */

    Note over Server: Server interprets headers<br/>(if --forwarded-allow-ips is set)

    Server->>Proxy: HTTP Response<br/>with correct HTTPS URLs

    Proxy->>Client: HTTPS Response
```

The **proxy** intercepts the original client request and adds the special *forwarded* headers (`X-Forwarded-*`) before passing the request to the **application server**.

        "Expected 'Sec-WebSocket-Accept' header value '$acceptExpected' but was '$headerAccept'",
      )
    }

    return response.socket
      ?: throw ProtocolException("Web Socket socket missing: bad interceptor?")
  }

  /**
   * This accepts a [BufferedSource] instead of using [Socket.source], just in case we've already
   * received data from the peer. This accepts a [BufferedSink] for symmetry with the source.
   */

   * as a **network interceptor**. It will strip the `Location` header of impacted responses to
   * prevent the redirect.
   *
   * ```
   * OkHttpClient client = client.newBuilder()
   *   .addNetworkInterceptor(new LegacyRedirectInterceptor())
   *   .build();
   * ```
   */
  internal class LegacyRedirectInterceptor : Interceptor {