request.kt

private val gatewayInformation = JSONObject().apply {
    put("gateway", "example")
    put("gatewayMerchantId", "exampleGatewayMerchantId")
}      

private val tokenizationSpecification = JSONObject().apply {
    put("type", "PAYMENT_GATEWAY")
    put("parameters", gatewayInformation)
}

private val cardPaymentMethod = JSONObject().apply {
    put("apiVersion", 2)
    put("apiVersionMinor", 0)
    put("tokenizationSpecification", tokenizationSpecification)
}