application code to omit a message.

 *  The challenge's scheme and realm are now non-null. If you are calling
    `new Challenge(scheme, realm)` you must provide non-null values. These were
    never null in challenges created by OkHttp, but could have been null in
    application code that creates challenges.

 *  New: The `TlsVersion` of a `Handshake` is now non-null. If you are calling

          call: Call,
          response: Response,
        ) {
          responses.offer(response.body.string())
        }
      }

    // Make the first request waiting until we get our auth challenge.
    val request = Request(server.url("/"))
    blockingAuthClient.newCall(request).enqueue(callback)
    val response1 = responses.take()
    assertThat(response1).isEqualTo("")

	public final fun matchesCertificate (Ljava/security/cert/X509Certificate;)Z
	public final fun matchesHostname (Ljava/lang/String;)Z
	public fun toString ()Ljava/lang/String;
}

public final class okhttp3/Challenge {
	public final fun -deprecated_authParams ()Ljava/util/Map;
	public final fun -deprecated_charset ()Ljava/nio/charset/Charset;
	public final fun -deprecated_realm ()Ljava/lang/String;

     */
    fun fastFallback(fastFallback: Boolean) =
      apply {
        this.fastFallback = fastFallback
      }

    /**
     * Sets the authenticator used to respond to challenges from origin servers. Use
     * [proxyAuthenticator] to set the authenticator for proxy servers.
     *
     * If unset, the [no authentication will be attempted][Authenticator.NONE].
     */