我试图使用以下代码发布更新到WeSub，但我收到错误
集线器模式无效

function sendWebSubNotification($topicUrl) {

    $response = Http::post("https://pubsubhubbub.appspot.com/", [
        'hub.mode' => 'publish',
        'hub.url' => $topicUrl,
    ], [
        'Content-Type' => 'application/x-www-form-urlencoded'
    ]);

    echo $response->getBody();

    if ($response->ok()) {
        // Ping successful
        return true;
    } else {
        // Ping failed
        return false;
    }

}