getToken BRI

public function getToken()
    {
        date_default_timezone_set('Asia/Jakarta');
        $timeStamp    = date('Y-m-d\TH:i:s.S\TP', time());
        $clientID     = '1YoKYKwitX05HpWcYuNtzvHHWOk6mvpc';
        $stringToSign = $clientID . '|' . $timeStamp;
        $curl         = curl_init();
        curl_setopt_array($curl, array(
            CURLOPT_URL            => 'https://sandbox.partner.api.bri.co.id/snap/v1.0/access-token/b2b',
            CURLOPT_RETURNTRANSFER => true,
            CURLOPT_ENCODING       => '',
            CURLOPT_MAXREDIRS      => 10,
            CURLOPT_TIMEOUT        => 0,
            CURLOPT_FOLLOWLOCATION => true,
            CURLOPT_HTTP_VERSION   => CURL_HTTP_VERSION_1_1,
            CURLOPT_CUSTOMREQUEST  => 'POST',
            CURLOPT_POSTFIELDS     => '{ "grantType": "client_credentials" }',
            CURLOPT_HTTPHEADER     => array(
                'X-SIGNATURE: ' . $stringToSign,
                'X-CLIENT-KEY: 1YoKYKwitX05HpWcYuNtzvHHWOk6mvpc',
                'X-TIMESTAMP: ' . $timeStamp,
                'Content-Type: application/json',
            ),
        ));

        $response = curl_exec($curl);
        curl_close($curl);
        echo $response;
    }