[Swift4] Post requests with a body parameter as ModelObject are malformed.

Description

In swift4 code generation, when custom templates introduced via -t command, the generated POST which require a modelObject as a parameter are incorrectly constructed.

Normally, the request function should only ask for the modelObject, however it asks for both the modelObject and the parameters inside the modelObject.

Example request and modelObject images are added below.

Example malformed post request.

Example post request body object.

Extra Clarification: Just to make it crystal clear, the request function should not ask for profileId & answers parameters in the above case since the body object already has the same parameters inside.

I'm using the 3.0.20 version swagger-codegen-cli.jar's mustache templates with some custom changes in them.
I thought that I may have broken something, so i tried to use the original files but the result is same as long as i introduce the templates with -t command.

Note that, If I do not specify templates then it functions correctly.

Swagger-codegen version

3.0.20

JSON & Config file

Below you can request specific json, which includes the request and the parameter modelObject definition

    "paths": {
        "/v1.3/pro/job_preferences": {
            "post": {
                "responses": {
                    "201": {
                        "description": "Created",
                        "schema": {
                            "$ref": "#/definitions/Void"
                        }
                    },
                    "404": {
                        "description": "NotFound",
                        "schema": {
                            "$ref": "#/definitions/ErrorMessage"
                        }
                    },
                    "500": {
                        "description": "InternalServerError",
                        "schema": {
                            "$ref": "#/definitions/ErrorMessage"
                        }
                    },
                    "401": {
                        "description": "Unauthorized",
                        "schema": {
                            "$ref": "#/definitions/ErrorMessage"
                        }
                    },
                    "400": {
                        "description": "BadRequest",
                        "schema": {
                            "$ref": "#/definitions/ErrorMessage"
                        }
                    }
                },
                "parameters": [
                    {
                        "schema": {
                            "$ref": "#/definitions/SaveProJobPreferencesViewModel"
                        },
                        "required": true,
                        "name": "jobPreferencesViewModel",
                        "in": "body"
                    }
                ],
                "produces": [
                    "application/json",
                    "text/json",
                    "text/html"
                ],
                "deprecated": false,
                "tags": [
                    "Pro"
                ],
                "consumes": [
                    "application/json",
                    "text/json",
                    "text/html",
                    "application/x-www-form-urlencoded"
                ],
                "operationId": "Pro_SaveProJobPreferences"
            }
        }
    },
    "definitions": {
        "SaveProJobPreferencesViewModel": {
            "type": "object",
            "properties": {
                "profile_id": {
                    "type": "integer",
                    "format": "int32"
                },
                "answers": {
                    "items": {
                        "$ref": "#/definitions/ProJobPreferenceAnswerViewModel"
                    },
                    "type": "array"
                }
            }
        }
    }
}

Command line used for generation

swagger-codegen generate -i api.json -l swift4 -c config.json -t MainApiMustaches

config.json

{
      "responseAs":"PromiseKit"
}

MainApiMustaches are the mustache files of version 3.0.20 swagger-codegen-cli.jar with some custom change in them.

I couldn't understand why the generator acts this way when even if the introduced templates are exactly the same templates extracted from the .jar the generation result changes with -t command.

Start with the Swift4 generation command, the extracted MainApiMustaches templates, and the supplied Swagger JSON/configuration. Compare generation with and without -t, focusing on the POST signature for jobPreferencesViewModel. Done means custom templates produce a request that accepts only the body model object, matching the non-template generation.