[Kotlin] API Input param with dot cannot be handled in kotlin code generated

Description

When generating kotlin client code with v2.3.1, if the api input parameter has a dot ".", the generated kotlin parameter will also contain the dot (e.g. model.paramName), which is an invalid kotlin variable name.

Swagger-codegen version

v2.3.1

Swagger declaration file content or url

Sample swagger spec with the problematic param pattern with dot "MobileDeviceUpdateDTO.Udid"
https://gist.github.com/joecklau/7cc6c168b9fc74ced352effec99b89a4

Command line used for generation

java -jar swagger-codegen-cli-2.3.1.jar generate -i swagger.json -l kotlin

Steps to reproduce

Just run it, and you will see the following java method created:
fun apiAuthLoginForTokenPost(mobileDeviceUpdateDTO.Udid : kotlin.String, _(someMoreParameters...)_ , phoneAreaCode: kotlin.String, phoneNumber: kotlin.String, email: kotlin.String) : JSendResponseLeft_Square_BracketAppTokenModelRight_Square_Bracket { val localVariableBody: kotlin.Any? = null val localVariableQuery: MultiValueMap = mapOf("mobileDeviceUpdateDTO.Udid" to listOf("**$mobileDeviceUpdateDTO.Udid**"), _(someMoreParameters...)_ , "phoneAreaCode" to listOf("$phoneAreaCode"), "phoneNumber" to listOf("$phoneNumber"), "email" to listOf("$email"), "password" to listOf("$password")) val localVariableHeaders: kotlin.collections.Map<kotlin.String,kotlin.String> = mapOf() _(someMoreCode...)_
in which "mobileDeviceUpdateDTO.Udid : kotlin.String" is invalid

Suggest a fix/enhancement

Skip the "." dot for kotlin param

Run the swagger-codegen-cli-2.3.1.jar command with the swagger.json sample from the linked gist and inspect the generated Kotlin method, especially the MobileDeviceUpdateDTO.Udid parameter. Trace the Kotlin generation entry point or template responsible for parameter names. Done means the generated Kotlin parameter is valid without the dot and the generated client no longer contains that invalid declaration.