[Go] Empty Struct Generated Which Should be a Typealias

Description

swagger-codegen does not create a correct GO representation for a OpenAPI 3.0 Model (from a schema definition) which would be ideally generated as a Go typealias.

Swagger-codegen version

This is the current version used in website: 3.0.10 (current tag)
openapi: 3.0.0

Swagger declaration file content or url

The following yaml snippet (openapi: 3.0.0) shows how the model is defined in section components/schemas:

components:
  schemas:
   Uint32:
      minimum: 0
      type: integer
      format: int32

This is basically a type integer which has a special format Uint32.

Command line used for generation

The code generator has been invoked from the Export feature from the website:

https://jdegre.github.io/

GenerateServer -> GoServer

Expected :
Go:

type ModelUint32 uint32

Actual:

/*
 * Nchf_ConvergedCharging
 *
 * ConvergedCharging Service    © 2019, 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). All rights reserved. 
 *
 * API version: 3.0.0.alpha-2
 * Generated by: Swagger Codegen (https://github.com/swagger-api/swagger-codegen.git)
 */
package swagger

type ModelUint32 struct {
}

As you can see, this is an empty struct and can not be used in any way.

Steps to reproduce

Well, this would require to setup a basic swagger spec and include the schema in the components section, then generate the code.

Related issues/PRs

Suggest a fix/enhancement

Start with the GoServer generator entry point and the components/schemas handling described in the issue, using the provided OpenAPI 3.0 schema and generation steps as a reproduction. Compare the generated ModelUint32 output with the expected Go typealias and verify that scalar schemas no longer produce an empty struct.