[Swift4] DefaultValue variable used in mustache template appears to not exist?

Description

It doesn't appear that the defaultValue variable is being generated when generating models with the language swift4.

Swagger-codegen version

2.4.0

Swagger declaration file content or url

definitions: {
  Order: {
    type: "object",
    properties: {
      id: {
        type: "integer",
        format: "int64"
      },
      petId: {
        type: "integer",
        format: "int64"
      },
      quantity: {
        type: "integer",
        format: "int32"
      },
      shipDate: {
        type: "string",
        format: "date-time"
      },
      status: {
        type: "string",
        description: "Order Status",
        enum: [
          "placed",
          "approved",
          "delivered"
        ]
      },
      complete: {
        type: "boolean",
        default: false
      }
    },
    xml: {
      name: "Order"
    }
  },
...

Command line used for generation

java -jar swagger-codegen-cli.jar generate \
-i https://petstore.swagger.io/v2/swagger.json \
-l swift4 -o /Users/.../.../.../.../.../SwaggerDemo -Dmodels

Steps to reproduce

1. Run the above command to produce swift models based off of the https://petstore.swagger.io/v2/swagger.json Open Api Specification.
2. Inspect the Order.swift model
3. The Order.swift model contains a class definition that looks like this:

public struct Order: Codable {

    public enum Status: String, Codable { 
        case placed = "placed"
        case approved = "approved"
        case delivered = "delivered"
    }
    public var _id: Int64?
    public var petId: Int64?
    public var quantity: Int?
    public var shipDate: Date?
    /** Order Status */
    public var status: Status?
    public var complete: Bool?

The complete Boolean property is defined with a default value, but the default value is not set:

      complete: {
        type: "boolean",
        default: false
      }

Related issues/PRs

Suggest a fix/enhancement

When I debug with -DdebugModels

java -DdebugModels -jar swagger-codegen-cli.jar generate \
  -i petstorecomplete.json \
  -l swift4

I see this output for the OrderClass:

{
      "baseName" : "complete",
      "getter" : "getComplete",
      "setter" : "setComplete",
      "datatype" : "Bool",
      "datatypeWithEnum" : "Bool",
      "name" : "complete",
      "defaultValueWithParam" : " = data.complete;",
      "baseType" : "Bool",
      "jsonSchema" : "{\n  \"type\" : \"boolean\",\n  \"default\" : false\n}",
      "exclusiveMinimum" : false,
      "exclusiveMaximum" : false,
      "hasMore" : false,
      "required" : false,
      "secondaryParam" : false,
      "hasMoreNonReadOnly" : false,
      "isPrimitiveType" : true,
      "isContainer" : false,
      "isNotContainer" : true,
      "isString" : false,
      "isNumeric" : false,
      "isInteger" : false,
      "isLong" : false,
      "isNumber" : false,
      "isFloat" : false,
      "isDouble" : false,
      "isByteArray" : false,
      "isBinary" : false,
      "isFile" : false,
      "isBoolean" : true,
      "isDate" : false,
      "isDateTime" : false,
      "isUuid" : false,
      "isListContainer" : false,
      "isMapContainer" : false,
      "isEnum" : false,
      "isReadOnly" : false,
      "vendorExtensions" : {
        "x-swift-optional-scalar" : true
      },
      "hasValidation" : false,
      "isInherited" : false,
      "nameInCamelCase" : "Complete",
      "isXmlAttribute" : false,
      "isXmlWrapped" : false
    } ],

But the defaultValue parameter used in the mustache file doesn't seem to exist at all:

  {{/description}}public var {{name}}: {{{datatype}}}{{^required}}?{{/required}}{{#defaultValue}} = {{{defaultValue}}}{{/defaultValue}}{{#objcCompatible}}{{#vendorExtensions.x-swift-optional-scalar}}

My only guess is that the defaultValue variable is no longer used or it's not being generated for some reason?

Thank you for any insight!

Start with the generated Order.swift model and the Swift4 Mustache template containing the defaultValue reference. Reproduce generation with the documented swagger-codegen command and inspect the debugModels output for the complete property. Done means the generated Swift model applies the schema's false default value, with generation output matching the intended template behavior.