Invalid enum var names are generated by multi-byte characters

Created by: osjupiter

Description

Hi. I have been using openapi-generator with definitions which contains multi-byte characters. When I wrote enum definitions which names contain only non-word characters(RegExp \W), invalid code generated. (All of enum names become "_".)

Are double-byte characters not allowed for enum names in OAS ? If it is valid, I hope these characters will be supported.

generated code

java

@JsonAdapter(PetType.Adapter.class)
public enum PetType {
  _("猫"), // cat   --compile error
  _("犬"); // dog

go

type PetType string
// List of PetType
const (
	 PetType = "猫" // compile error
	 PetType = "犬"
)

openapi-generator version

3.2.3-SNAPSHOT

OpenAPI declaration file content or url

swagger: "2.0"
info:
  title: "example"
  version: "1.0"
paths:
  /pet:
    post:
      parameters:
        - in: body
          name: data
          schema:
            type: object
            properties:
              animal:
                $ref: "#/definitions/PetType"
      responses:
        "200":
          description: ok
definitions:
  PetType:
    type: string
    enum:
      - 猫
      - 犬
    x-enum-names:
      - Cat
      - Dog

Command line used for generation

java -jar openapi-generator-cli-3.2.3-20180824.092221-7.jar generate  -i sample.yaml -g java -o dest

Steps to reproduce

just generated

Related issues/PRs

I could not find it.

Suggest a fix/enhancement

I always create a customized config class and add x-enum-names extension by overriding postProcessModelsEnum and updateCodegenPropertyEnum like this.

I think it is not good to positively use multi-byte characters as an api parameter.
So it is enough to be able to use it by extension.

Thanks.