RestHandler::getCheckoutPayParams

private function getCheckoutPayParams(Payment $payment, Request $request): array
{
	$params = [];

	$checkoutSettings = $this->getHandlerSettings()['CHECKOUT_DATA'];
	if (isset($checkoutSettings['FIELDS']))
	{
		$params = $this->getQueryDataFromFields($payment, $checkoutSettings['FIELDS']);
	}

	$requestData = $request->toArray();
	foreach ($requestData as $field => $value)
	{
		if (isset($checkoutSettings['FIELDS'][$field]))
		{
			$params[$field] = $value;
		}
	}

	return array_merge($params, $this->getSystemParams($payment));
}