[GO] Invalid code generated when enum contains integers

[will-in-wi]

Description

Per the Golang spec, the first character in an identifier must be a letter. When an enum contains strings which are numbers (as in IP versions), these are interpolated into invalid code.

Swagger-codegen version

3.0.30

Swagger declaration file content or url

openapi: 3.0.3
info:
  title: Test
  version: 1.0.0
paths:
  /test/:
    post:
      responses:
        '200':
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/IPAddressTypeEnum'
          description: null
components:
  schemas:
    IPAddressTypeEnum:
      enum:
      - '4'
      - '6'
      type: string

Command line used for generation

swagger-codegen generate -i ../schema.yml -l go

Steps to reproduce

Save above schema into file, run the command in an empty folder, and take a look at model_ip_address_type_enum.go. The identifiers start with numbers, which isn't valid in Go.

// List of IPAddressTypeEnum
const (
	4__IpAddressTypeEnum IpAddressTypeEnum = "4"
	6__IpAddressTypeEnum IpAddressTypeEnum = "6"
)

Suggest a fix/enhancement

I'm not really sure what the best approach would be. In my specific case, I'm manually changing them to v4 and v6. Maybe prepending an i for i4 and i6 to indicate integer? It isn't especially pretty either way.

I'm new to this codebase, so if I'm doing something weirdly or misunderstanding the purpose of something, please set me on the right track. Thank you all so much for your work on this project!