[RUBY] Deserialization should honor discriminator field when deserializing collection

Description

Let's say I have collection that contains LogicalRouterPort in API spec:

"LogicalRouterPortListResult": {
      "allOf": [
        {
          "required": [
            "results"
          ],
          "type": "object",
          "properties": {
            "results": {
              "items": {
                "$ref": "#/definitions/LogicalRouterPort"
              },
              "type": "array",
              "description": "Logical router port list results",
              "title": "Logical router port list results"
            }          }        }      ]

LogicalRouterPort has with resource_type as discriminator.

"LogicalRouterPort": {
      "allOf": [   
        {
          "discriminator": "resource_type",
          "required": [
            "resource_type"
          ],
          "type": "object",
          "properties": {
            "resource_type": {
              "enum": [
                "LogicalRouterLinkPortOnTIER0",
                "LogicalRouterLinkPortOnTIER1",
              ],
              "type": "string",
            }, }   }  ] }

and here is a inherited class of LogicalRouterPort

"LogicalRouterLinkPortOnTIER0": {
      "allOf": [ {
          "properties": {
            "linked_logical_router_port_id": {
              "readOnly": true,
              "type": "string",
            }
          },
          "type": "object" }   ],  }

I have JSON that represents LogicalRouterPortListResult and actual values in the results field are objects of class LogicalRouterLinkPortOnTIER0 with resource_type set to LogicalRouterLinkPortOnTIER0.
So when I'm deserializing LogicalRouterPortListResult I would expect ruby object to have proper ruby type in results field. Instead my LogicalRouterPortListResult has results of type LogicalRouterPort.
This is happening because my ruby class LogicalRouterPortListResult has hardcoded type of LogicalRouterPort and it uses this type (instead of getting actual type from resource_type) to deserialize JSON.

    def self.swagger_types {
          <reducted>
          :'results' => :'Array<LogicalRouterPort>'
      }
    end

Swagger-codegen version

2.3.1

Swagger declaration file content or url

This is description of whole project that includes objects from above
api spec

Command line used for generation

swagger-codegen generate -i ./data/nsx_api.json -l ruby -o ./lib/nsxt -c ./data/config.json -t ./data/swagger-nsxt-template

Steps to reproduce

Related issues/PRs

Suggest a fix/enhancement

As a workaround I've added

unless value[:resource_type ].nil?
    type = value[:resource_type].to_sym
end
temp_model = {{moduleName}}.const_get(type).new
temp_model.build_from_hash(value)

in deserialization code here

Am I missing something? Is it really a bug do I just have incorrect spec file?

Start with the Ruby deserialization logic in modules/swagger-codegen/src/main/resources/ruby/base_object.mustache, then generate the client with the provided command and nsx_api.json. Compare deserialization of LogicalRouterPortListResult.results when resource_type identifies LogicalRouterLinkPortOnTIER0. Done means generated Ruby objects in the collection honor the discriminator instead of always using LogicalRouterPort.