[BUG][SWIFT4] Inherited enumerations are not being generated correctly

[lopesmcc]

Description

Whenever a definition is inheriting enumeration fields (using allOf), these end up being generated without any options.

public enum Status: String, Codable {
}

Those same enumerations are being generated correctly on the original definition.

Our spec is still using swagger 2.0.

openapi-generator version

Happening on v3.3.4. Was using swagger-codegen before and did not have this issue.

OpenAPI declaration file content or url

ParentObject:
    type: object
    required:
      - id
      - status
    properties:
      id:
        type: string
      status:
        type: string
        enum:
          - generate
          - activate
          - suspend
          - refund
          - expire
          - burn
  NamedChildObject:
    allOf:
      - $ref: '#/definitions/ParentObject'
      - type: object
        properties:
          name:
          type: string

Using the example above, NamedObject will look like:

public struct NamedChildObject: Codable {

    public enum Status: String, Codable {
    }
    public var _id: String
    public var status: Status

    public init(_id: String, status: Status) {
        self._id = _id
        self.status = status
    }

    public enum CodingKeys: String, CodingKey { 
        case _id = "id"
        case status
    }
}

[lopesmcc]

Seems to me that at DefaultCodegen.java:312, we should be iterating through the model allVars, and not only vars. This way, it would generate the enumVars metadata even for inherited data.

Not sure what kind of impact this would have for other generators.