[BUG] [GROOVY] Enums are generated as empty classes

Description

I'm trying to generate a groovy model from an openapi spec. Sadly enums are always generated es an empty class. If I use the java generator I get a correct enum with all the defined values inside. So my guess is there is a bug in the groovy generator.

My schema looks like this:

    GreetingType:
      type: string
      enum:
      - FRIENDLY
      - FORMAL

and the generated groovy code looks sadly like this:

@Canonical
class GreetingType {
}

I was expecting something like:

enum GreetingType {
  FRIENDLY, 
  FORMAL
}

openapi-generator version

6.2.1

OpenAPI declaration file content or url

openapi: 3.0.1
info:
  title: test-bas
  version: 1.0.0-SNAPSHOT
servers:
- url: http://localhost:8080/
  description: Generated server url
paths:
  /rest/greet/{name}:
    get:
      tags:
      - rest-service-app
      operationId: greet
      parameters:
      - name: name
        in: path
        required: true
        schema:
          type: string
      responses:
        "200":
          description: OK
          content:
            '*/*':
              schema:
                $ref: '#/components/schemas/Greeting'
components:
  schemas:
    Greeting:
      type: object
      properties:
        type:
          $ref: '#/components/schemas/GreetingType'
        text:
          type: string
    GreetingType:
      type: string
      enum:
      - FRIENDLY
      - FORMAL

Generation Details

I use the maven plugin. These are my settings:

         <plugin>
                <groupId>org.openapitools</groupId>
                <artifactId>openapi-generator-maven-plugin</artifactId>
                <version>6.2.1</version>
                <executions>
                    <execution>
                        <goals>
                            <goal>generate</goal>
                        </goals>
                        <configuration>
                            <inputSpec>${project.basedir}/resources/openapi.yml</inputSpec>
                            <generatorName>groovy</generatorName>
                            <generateApis>false</generateApis>
                            <generateSupportingFiles>false</generateSupportingFiles>
                        </configuration>
                    </execution>
                </executions>
            </plugin>

Steps to reproduce

Use the groovy generator to generate models from an openapi spec with enums

Related issues/PRs

I could not find any...

Suggest a fix

Usable enums please 🙂

OpenAPITools / openapi-generator