App\Ninja\PaymentDrivers\BasePaymentDriver::attemptVoidPayment PHP Method

    protected function attemptVoidPayment($response, $payment, $amount)
    {
        // Partial refund not allowed for unsettled transactions
        return $amount == $payment->amount;
    }

 protected function attemptVoidPayment($response, $payment, $amount)
 {
     if (!parent::attemptVoidPayment($response, $payment, $amount)) {
         return false;
     }
     $data = $response->getData();
     if ($data instanceof \Braintree\Result\Error) {
         $error = $data->errors->deepAll()[0];
         if ($error && $error->code == 91506) {
             return true;
         }
     }
     return false;
 }