[BUG] [JAVA] Property "useOneOfInterfaces" seems to be ignored during generation since version v7.13

[neffets74]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
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Description

In my specification I have a "oneOf" relation between two components, a interface ExINterface and a class ExObject1 implementing this interface (see specification snippet below).

When generating the code out of the specification with plugin version 7.12.0 I get the expected result:

public class ExObject1 implements ExInterface

But when generating the code with plugin version 7.13.0, the generated class does not implement the interface:

public class ExObject1

The interface class itself is not even generated.

openapi-generator version

v7.13.0

OpenAPI declaration file content or url

openapi: 3.0.3
info:
    title: Example API
    description: This is an example API specification serving as error reproducer
    version: 1.0.0
paths:
  /example:
    get:
      summary: Example endpoint
      description: This is an example endpoint
      operationId: getExample
      parameters:
        - name: exampleParam
          in: query
          required: true
          description: An example query parameter
          schema:
            type: string
      responses:
        '200':
          description: Successful response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ExInterface'
components:
  schemas:
    ExInterface:
      oneOf:
        - $ref: '#/components/schemas/ExObject1'
    ExObject1:
      type: object
      properties:
        name:
          type: string
          description: The name of the object

Generation Details

Using the following code gen options:

{
  "generatorName": "java",
  "library": "google-api-client",

  "sourceFolder": ".",
  "basePackage": "sk.example.base",
  "configPackage": "sk.example.config",
  "modelPackage": "sk.example.model",
  "apiPackage": "sk.example.client",

  "disallowAdditionalPropertiesIfNotPresent": true,
  "interfaceOnly": true,
  "legacyDiscriminatorBehavior": false,
  "openApiNullable": false,
  "useBeanValidation": true,
  "useEnumCaseInsensitive": true,
  "useJakartaEe": true,
  "useOneOfInterfaces": true,
  "useOptional": false
}

Steps to reproduce

Calling "./gradlew openapiGenerate" and reviewing the generated class "ExObject1".

Related issues/PRs

Suggest a fix

[Mattias-Sehlstedt]

Hi,

This is tied to my fix here #21043. It fixed so that the generator normalization is now working as advertised. If it is of interest to get an interface for a oneOf with a single subSchema, then I would investigate turning off the SIMPLIFY_ONEOF_ANYOF normalization.

[neffets74]

Thank you for clarification.
Unfortunately, it seems not to be straight forward, to disable the normalization when using the openapi-generator-gradle-plugin.
At least I could not find an according configuration option.

[Mattias-Sehlstedt]

The settings are documented here, and the plugin usage here. When I have used their suggested structure

It works as expected and it affects the normalizer's behavior.

E.g., something similar to:

openapiNormalizer.set([
  DISABLE_ALL: "true"
])

in your gradle task.

[neffets74]

Great, it works now as expected. Thank you. I will close the issue.