[java] no inner enums generated on arrays of enums

Created by: jmini

Description

When an model is an array of enums, the type is not the correct one.

openapi-generator version

3.0.0-SNAPSHOT

OpenAPI declaration file content or url

openapi: 3.0.1
info:
  title: OpenAPI test
  description: Example spec
  version: 1.0.0
servers:
  - url: 'http://api.company.xyz/call'
paths:
  /some/ping:
    get:
      operationId: op1
      responses:
        '200':
          description: Ok
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ArrayOfEnum'
components:
  schemas:
    ArrayOfEnum:
      type: array
      items:
        type: string
        enum:
          - val1
          - val2
          - val3
          - val4

Command line used for generation

java client generator, without any particular option

JavaClientCodegen config = new org.openapitools.codegen.languages.JavaClientCodegen();
config.setArtifactId(artifactId);
config.setJava8Mode(true);

Path outputDirPath = Paths.get(outputDir);

config.setHideGenerationTimestamp(true);
config.setOutputDir(outputDir);

final OpenAPIParser openApiParser = new OpenAPIParser();
final ParseOptions options = new ParseOptions();
final OpenAPI openAPI = openApiParser.readLocation(inputSpec, null, options).getOpenAPI();

final ClientOptInput opts = new ClientOptInput();
opts.setConfig(config);
opts.setOpenAPI(openAPI);
opts.setOpts(new ClientOpts());
new DefaultGenerator().opts(opts).generate();

Suggest a fix/enhancement

Model class is:

public class ArrayOfEnum extends ArrayList<String> {
//...
}

Should be a ArrayList of the enum type (maybe an inner enum) instead of String

Work around:

Use an indirection over $ref:

openapi: 3.0.1
info:
  title: OpenAPI test
  description: Example spec
  version: 1.0.0
servers:
  - url: 'http://api.company.xyz/call'
paths:
  /some/ping:
    get:
      operationId: op1
      responses:
        '200':
          description: Ok
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ArrayOfEnum'
components:
  schemas:
    ArrayOfEnum:
      type: array
      items:
        $ref: '#/components/schemas/SomeEnum'
    SomeEnum:
      type: string
      enum:
        - val1
        - val2
        - val3
        - val4