public function batchSubscribeAddressTransactions($identifier, $batchData) {
        $postData = [];
        foreach ($batchData as $record) {
            $postData[] = [
                'event_type' => 'address-transactions',
                'address' => $record['address'],
                'confirmations' => isset($record['confirmations']) ? $record['confirmations'] : 6,
            ];
        }
        $response = $this->blocktrailClient->post("webhook/{$identifier}/events/batch", null, $postData, RestClient::AUTH_HTTP_SIG);
        return self::jsonDecode($response->body(), true);
    }