[Swift 3] body parameter cannot be an integer

Description

The generation of the Swift-3 client produces wrong code, when it comes to generating a call that has a parameter which is of integer (or more generally raw-type).

Swagger-codegen version

reproduced with both

• https://editor.swagger.io/
• latest editor from github

Swagger declaration file content or url

 /users/cards:
    delete:
      description: Delete a card from a user
      produces:
        - application/json
      parameters:
        - in: body
          name: cardSlot
          description: the card that will be deleted
          required: true
          schema:
            type: integer
            format: int32
      responses:
        '200':
          description: Success

Command line used for generation

Steps to reproduce

Related issues/PRs

https://github.com/swagger-api/swagger-codegen/issues/5639
https://github.com/swagger-api/swagger-codegen/issues/5480

Suggest a fix/enhancement

Generated code looks like this:

DefaultAPI.swift:
open class func usersCardsDeleteWithRequestBuilder(cardSlot: Int32) -> RequestBuilder<Void> {
        let path = "/users/cards"
        let URLString = SwaggerClientAPI.basePath + path
        let parameters = cardSlot.encodeToJSON() as? [String:AnyObject]    //-> this will fail and result in nil because of:

Extensions.swift:
extension Int32: JSONEncodable {
    func encodeToJSON() -> Any { return NSNumber(value: self as Int32) }
}

why should the parameter be always a dictionary?

As a workaround, I will change my yaml, to contain an object.. but I think the above case should be supported as well.

Use the supplied /users/cards Swagger YAML and inspect the generated DefaultAPI.swift and Extensions.swift files, focusing on the integer body parameter and its JSON encoding. Reproduce Swift 3 client generation with the referenced Swagger Editor versions, then verify that the generated call supports a raw integer body without the reported dictionary cast failure.