[BUG] [Go] generator generates uncompilable model code in the NullableXY struct's Unset function

Description

If I generate a Go model from a schema which has an array typed component and use the --generate-alias-as-model the generated go code is not compiling.

A snippet from the generated code:

type NullableA struct {
	value A    <----- value is not a pointer
	isSet bool
}

...

func (v *NullableA) Unset() {
	v.value = nil   <----- this can't be nil
	v.isSet = false
}

The origin of the problem is around the nullable model template where it seems the value is not getting that * to become a pointer.
openapi-generator/src/main/resources/go/nullable_model.mustache

type Nullable{{{classname}}} struct {
	value {{^isArray}}{{^isFreeFormObject}}*{{/isFreeFormObject}}{{/isArray}}{{{classname}}}
	isSet bool
}

openapi-generator version

tested with openapitools/openapi-generator-cli:6.0.0 and later

OpenAPI declaration file content or url

openapi: 3.0.1
info:
  title: test
  version: 1.0.0
  description: test
paths: {}
components:
  schemas:
    A:
      type: array
      items:
        type: object
        properties:
          B:
            type: integer

Generation Details

Used an array typed component and the --generate-alias-as-model flag with the go generator.

Steps to reproduce

openapi-generator-cli generate --generate-alias-as-model -i A.yaml -g go -o .

Related issues/PRs

Suggest a fix

In the openapi-generator/src/main/resources/go/nullable_model.mustache template:

• either the pointer declaration should not be skipped in case the model isArray
• or use the same filtering conditions in the Unset ({{^isArray}}{{^isFreeFormObject}}) as this can also be a problem in case of models which are isFreeFormObjects as the nil assignemnt could fail in those cases too.

Start with openapi-generator/src/main/resources/go/nullable_model.mustache and reproduce the issue using the provided A.yaml and generate command with --generate-alias-as-model. Compare the pointer declaration with the Unset function for array and free-form models. Done means the generated Go model compiles and NullableA.Unset does not assign nil to a non-pointer value.