[Kotlin] int type results in null pointer exception

Description

When generating swagger for our kotlin project, we hit a null pointer exception. After looking into it, it seems to originate from using int as a type (as opposed to Integer, int32, etc)

[main] WARN io.swagger.codegen.DefaultCodegen - Type is NULL for Serializable Parameter: orderDetailId
Exception in thread "main" java.lang.RuntimeException: Could not process operation:
Tag: Tag {
name: DocumentInfo
description: null
externalDocs: null
extensions:{}}
Operation: V1DocumentInfoUploadPost
Resource: post /v1/DocumentInfo/upload

Exception: null
at io.swagger.codegen.DefaultGenerator.processOperation(DefaultGenerator.java:940)
at io.swagger.codegen.DefaultGenerator.processPaths(DefaultGenerator.java:819)
at io.swagger.codegen.DefaultGenerator.generateApis(DefaultGenerator.java:439)
at io.swagger.codegen.DefaultGenerator.generate(DefaultGenerator.java:754)
at io.swagger.codegen.cmd.Generate.run(Generate.java:285)
at io.swagger.codegen.SwaggerCodegen.main(SwaggerCodegen.java:35)
Caused by: java.lang.NullPointerException
at io.swagger.codegen.languages.AbstractKotlinCodegen.toModelName(AbstractKotlinCodegen.java:445)
at io.swagger.codegen.languages.AbstractKotlinCodegen.getSwaggerType(AbstractKotlinCodegen.java:252)
at io.swagger.codegen.DefaultCodegen.fromProperty(DefaultCodegen.java:1594)
at io.swagger.codegen.DefaultCodegen.fromParameter(DefaultCodegen.java:2536)
at io.swagger.codegen.DefaultCodegen.fromOperation(DefaultCodegen.java:2241)
at io.swagger.codegen.DefaultGenerator.processOperation(DefaultGenerator.java:889)
... 5 more

Swagger-codegen version

Master

Swagger declaration file content or url

"/v1/DocumentInfo/upload": {
"post": {
"tags": [
"DocumentInfo"
],
"operationId": "V1DocumentInfoUploadPost",
"consumes": [
"multipart/form-data",
],
"produces": [

    ],
    "parameters": [
      {
        "name": "orderDetailId",
        "in": "query",
        "description": "OrderDetailId",
        "required": true,
        "type": "int"
      }
    ],
    "responses": {
      "204": {
        "description": "Success"
      }
    }
  }
}

Command line used for generation

swagger-codegen generate -i swagger.json -l kotlin -o SwaggerClient/

Steps to reproduce

Have a property with type int as a parameter.

Start in AbstractKotlinCodegen.toModelName and follow how the int parameter reaches getSwaggerType and fromProperty. Run the supplied swagger-codegen generate command with the declaration shown; done means Kotlin generation handles the int parameter without the null pointer exception.