Selenium WebDriver POST cookie错误 - UnsupportedCommandException

Question

我正在尝试为会话设置Cookie

self::$serverUrl="http://localhost:4444/wd/hub";
self::$browser="firefox";
self::$additionalCapabilities=[];
self::$webdriver = new \WebDriver\WebDriver(self::$serverUrl);
self::$webdriver->session(self::$browser, self::$additionalCapabilities);

self::$session->postCookie('{"cookie":{"name":"test_cookie","value":"1"}}');

它返回UnsupportedCommandException：

    [state] => unhandled error
    [sessionId] =>
    [hCode] => 103271444
    [value] => Array
        (
            [additionalInformation] =>
Driver info: driver.version: unknown
            [localizedMessage] => POST /session/99800243-d310-4a16-b84f-2c754d315ded/cookie/{"cookie":{"name":"test_cookie","value":"1"}}
Build info: version: '2.48.2', revision: '41bccdd', time: '2015-10-09 19:59:12'
System info: host: '00L11-036', ip: '10.22.23.84', os.name: 'Windows 7', os.arch: 'amd64', os.version: '6.1', java.version: '1.8.0_66'
Driver info: driver.version: unknown
            [systemInformation] => System info: host: '00L11-036', ip: '10.22.23.84', os.name: 'Windows 7', os.arch: 'amd64', os.version: '6.1', java.version: '1.8.0_66'
            [supportUrl] =>
            [cause] =>
            [stackTrace] => Array
                (
                    [0] =>
                    [1] =>
                    [2] =>
                    [3] =>
                    [4] =>
                    [5] =>
                    [6] =>
                    [7] =>
                    [8] =>
                    [9] =>
                    [10] =>
                    [11] =>
                    [12] =>
                    [13] =>
                    [14] =>
                    [15] =>
                    [16] =>
                    [17] =>
                    [18] =>
                )

            [suppressed] => Array
                (
                )

            [message] => POST /session/99800243-d310-4a16-b84f-2c754d315ded/cookie/{"cookie":{"name":"test_cookie","value":"1"}}
Build info: version: '2.48.2', revision: '41bccdd', time: '2015-10-09 19:59:12'
System info: host: '00L11-036', ip: '10.22.23.84', os.name: 'Windows 7', os.arch: 'amd64', os.version: '6.1', java.version: '1.8.0_66'
Driver info: driver.version: unknown
            [hCode] => 495357701
            [class] => org.openqa.selenium.UnsupportedCommandException
            [buildInformation] =>
        )

    [class] => org.openqa.selenium.remote.Response
    [status] => 13

我做错了什么？

我在Windows上使用selenium-server-standalone-2.48.2。