[Fix] [Regression] Resolve the discriminator type from a 3.1 sibling

.github/workflows/samples-java-client-jdk17.yaml

@@ -7,6 +7,7 @@ on:
       - samples/client/petstore/java/webclient-jakarta/**
       - samples/client/petstore/java/restclient-*/**
       - samples/client/others/java/webclient-sealedInterface/**
+      - samples/client/others/java/webclient-sealedInterface_3_1/**
       - samples/client/petstore/java/webclient-useSingleRequestParameter/**
       - samples/client/others/java/restclient-enum-in-multipart/**
   pull_request:
@@ -15,6 +16,7 @@ on:
       - samples/client/petstore/java/webclient-jakarta/**
       - samples/client/petstore/java/restclient-*/**
       - samples/client/others/java/webclient-sealedInterface/**
+      - samples/client/others/java/webclient-sealedInterface_3_1/**
       - samples/client/petstore/java/webclient-useSingleRequestParameter/**
       - samples/client/others/java/restclient-enum-in-multipart/**
 jobs:
@@ -34,6 +36,7 @@ jobs:
           - samples/client/petstore/java/restclient-useSingleRequestParameter
           - samples/client/petstore/java/restclient-useSingleRequestParameter-static
           - samples/client/others/java/webclient-sealedInterface
+          - samples/client/others/java/webclient-sealedInterface_3_1
           - samples/client/petstore/java/webclient-useSingleRequestParameter
           - samples/client/others/java/restclient-enum-in-multipart
     steps:

bin/configs/java-webclient-sealedInterface-3.1.yaml

@@ -0,0 +1,10 @@
+generatorName: java
+outputDir: samples/client/others/java/webclient-sealedInterface_3_1
+library: webclient
+inputSpec: modules/openapi-generator/src/test/resources/3_1/oneof_polymorphism_and_inheritance.yaml
+templateDir: modules/openapi-generator/src/main/resources/Java
+additionalProperties:
+  artifactId: sealed-interface-webclient
+  hideGenerationTimestamp: "true"
+  useOneOfInterfaces: true
+  useSealedOneOfInterfaces: true

modules/openapi-generator/src/main/java/org/openapitools/codegen/DefaultCodegen.java

@@ -3301,7 +3301,7 @@ private CodegenProperty discriminatorFound(String composedSchemaName, Schema sc,
         }
 
         if (refSchema.getProperties() != null && refSchema.getProperties().get(discPropName) != null) {
-            Schema discSchema = ModelUtils.getReferencedSchema(openAPI, (Schema) refSchema.getProperties().get(discPropName));
+            Schema discSchema = ModelUtils.getReferencedSchema(openAPI, getDiscriminatorSchema(refSchema, discPropName));
             CodegenProperty cp = new CodegenProperty();
             if (ModelUtils.isStringSchema(discSchema)) {
                 cp.isString = true;
@@ -3632,14 +3632,7 @@ protected CodegenDiscriminator createDiscriminator(String schemaName, Schema sch
         // FIXME: there are other ways to define the type of the discriminator property (inline
         //  for example). Handling those scenarios is too complicated for me, I'm leaving it for
         //  the future..
-        String propertyType =
-                Optional.ofNullable(schema.getProperties())
-                        .map(p -> (Schema<?>) p.get(discriminatorPropertyName))
-                        .map(Schema::get$ref)
-                        .map(ModelUtils::getSimpleRef)
-                        .map(this::toModelName)
-                        .orElseGet(() -> typeMapping.get("string"));
-        discriminator.setPropertyType(propertyType);
+        discriminator.setPropertyType(getDiscriminatorPropertyType(schema, discriminatorPropertyName));
 
         // check to see if the discriminator property is an enum string
         boolean isEnum = Optional
@@ -3703,6 +3696,39 @@ protected CodegenDiscriminator createDiscriminator(String schemaName, Schema sch
         return discriminator;
     }
 
+    /**
+     * Get the Schema for the discriminator type. Requires special handling due to siblings from OAS 3.1.
+     * An example of a sibling is an enum-ref that has its own description. This will lead to the enum being
+     * referenced as an allOf that in turn has a ref, rather than a regular ref directly to the enum.
+     *
+     * @param schema            The input OAS schema.
+     * @param discriminatorName The name of the discriminator property.
+     */
+    protected Schema getDiscriminatorSchema(Schema schema, String discriminatorName) {
+        if (schema.getProperties() == null) {
+            return null;
+        }
+        Schema discSchema = (Schema) schema.getProperties().get(discriminatorName);
+        if (ModelUtils.isAllOf(discSchema)) {
+            discSchema = (Schema) discSchema.getAllOf().get(0);
+        }
+        return discSchema;
+    }
+
+    /**
+     * Get the property type for the discriminator
+     *
+     * @param schema                    The input OAS schema.
+     * @param discriminatorPropertyName The name of the discriminator property.
+     */
+    protected String getDiscriminatorPropertyType(Schema schema, String discriminatorPropertyName) {
+        return Optional.ofNullable(getDiscriminatorSchema(schema, discriminatorPropertyName))
+                .map(Schema::get$ref)
+                .map(ModelUtils::getSimpleRef)
+                .map(this::toModelName)
+                .orElseGet(() -> typeMapping.get("string"));
+    }
+
     /**
      * Handle the model for the 'additionalProperties' keyword in the OAS schema.
      *

modules/openapi-generator/src/test/java/org/openapitools/codegen/DefaultCodegenTest.java

@@ -1131,6 +1131,23 @@ public void testDiscriminatorWithCustomMapping() {
         assertTrue(personModel.getHasDiscriminatorWithNonEmptyMapping());
     }
 
+    @Test
+    public void testEnumDiscriminatorWithDescriptionOverridden3_1() {
+        final OpenAPI openAPI = TestUtils.parseFlattenSpec("src/test/resources/3_1/oneof_polymorphism_and_inheritance.yaml");
+        new OpenAPINormalizer(openAPI, Map.of()).normalize();
+        DefaultCodegen codegen = new DefaultCodegen();
+        codegen.setUseOneOfInterfaces(true);
+
+        Schema fruit = openAPI.getComponents().getSchemas().get("Fruit");
+        codegen.setOpenAPI(openAPI);
+        CodegenModel fruitModel = codegen.fromModel("Fruit", fruit);
+        assertTrue(fruitModel.getHasDiscriminatorWithNonEmptyMapping());
+        assertTrue(fruitModel.discriminator.getIsEnum());
+        assertEquals("FruitType", fruitModel.discriminator.getPropertyType());
+        assertEquals("test", fruitModel.getVars().get(0).description);
+        assertTrue(fruitModel.getVars().get(0).isEnumRef);
+    }
+
     @Test
     public void testParentName() {
         final OpenAPI openAPI = TestUtils.parseFlattenSpec("src/test/resources/3_0/allOf.yaml");

modules/openapi-generator/src/test/java/org/openapitools/codegen/java/JavaClientCodegenTest.java

@@ -4063,4 +4063,13 @@ public void testOneOfInterfaceWithAnnotation() {
                 .isInterface()
                 .assertTypeAnnotations().containsWithName("SuppressWarnings");
     }
+
+    @Test
+    public void testOneOfInterfaceWithEnumDiscriminatorHavingCustomDescription3_1() {
+        final Map<String, File> files = generateFromContract("src/test/resources/3_1/oneof_polymorphism_and_inheritance.yaml", WEBCLIENT,
+                Map.of(USE_ONE_OF_INTERFACES, "true"));
+        JavaFileAssert.assertThat(files.get("Fruit.java"))
+                .isInterface()
+                .fileContains("public FruitType getFruitType()");
+    }
 }

modules/openapi-generator/src/test/resources/3_1/oneof_polymorphism_and_inheritance.yaml

@@ -0,0 +1,253 @@
+openapi: 3.1.0
+info:
+  title: ByRefOrValue
+  description: >
+    This tests for a oneOf interface representation
+  version: 0.0.1
+servers:
+  - url: "http://localhost:8080"
+tags:
+  - name: Foo
+  - name: Bar
+paths:
+  /foo:
+    get:
+      tags:
+        - Foo
+      summary: GET all Foos
+      operationId: getAllFoos
+      responses:
+        '200':
+          $ref: '#/components/responses/200FooArray'
+    post:
+      tags:
+        - Foo
+      summary: Create a Foo
+      operationId: createFoo
+      requestBody:
+        $ref: '#/components/requestBodies/Foo'
+      responses:
+        '201':
+          $ref: '#/components/responses/201Foo'
+  /bar:
+    post:
+      tags:
+        - Bar
+      summary: Create a Bar
+      operationId: createBar
+      requestBody:
+        required: true
+        content:
+          'application/json':
+            schema:
+              $ref: '#/components/schemas/Bar_Create'
+      responses:
+        200:
+          description: Bar created
+          content:
+            'application/json':
+              schema:
+                $ref: '#/components/schemas/Bar'
+
+components:
+  schemas:
+    Addressable:
+      type: object
+      properties:
+        href:
+          type: string
+          description: Hyperlink reference
+        id:
+          type: string
+          description: unique identifier
+      description: Base schema for addressable entities
+    Extensible:
+      type: object
+      properties:
+        "@schemaLocation":
+          type: string
+          description: A URI to a JSON-Schema file that defines additional attributes
+            and relationships
+        "@baseType":
+          type: string
+          description: When sub-classing, this defines the super-class
+        "@type":
+          type: string
+          description: When sub-classing, this defines the sub-class Extensible name
+      required:
+        - '@type'
+    Entity:
+      type: object
+      discriminator:
+        propertyName: '@type'
+      allOf:
+        - "$ref": "#/components/schemas/Addressable"
+        - "$ref": "#/components/schemas/Extensible"
+    EntityRef:
+      type: object
+      discriminator:
+        propertyName: '@type'
+      description: Entity reference schema to be use for all entityRef class.
+      properties:
+        name:
+          type: string
+          description: Name of the related entity.
+        '@referredType':
+          type: string
+          description: The actual type of the target instance when needed for disambiguation.
+      allOf:
+        - $ref: '#/components/schemas/Addressable'
+        - "$ref": "#/components/schemas/Extensible"
+    FooRefOrValue:
+      type: object
+      oneOf:
+        - $ref: "#/components/schemas/Foo"
+        - $ref: "#/components/schemas/FooRef"
+      discriminator:
+        propertyName: "@type"
+    Foo:
+      type: object
+      properties:
+        fooPropA:
+          type: string
+        fooPropB:
+          type: string
+      allOf:
+        - $ref: '#/components/schemas/Entity'
+    FooRef:
+      type: object
+      properties:
+        foorefPropA:
+          type: string
+      allOf:
+        - $ref: '#/components/schemas/EntityRef'
+    BarRef:
+      type: object
+      allOf:
+        - $ref: '#/components/schemas/EntityRef'
+    Bar_Create:
+      type: object
+      properties:
+        barPropA:
+          type: string
+        fooPropB:
+          type: string
+        foo:
+          $ref: '#/components/schemas/FooRefOrValue'
+      allOf:
+        - $ref: '#/components/schemas/Entity'
+    Bar:
+      type: object
+      required:
+        - id
+      properties:
+        id:
+          type: string
+        barPropA:
+          type: string
+        fooPropB:
+          type: string
+        foo:
+          $ref: '#/components/schemas/FooRefOrValue'
+      allOf:
+        - $ref: '#/components/schemas/Entity'
+    BarRefOrValue:
+      type: object
+      oneOf:
+        - $ref: "#/components/schemas/Bar"
+        - $ref: "#/components/schemas/BarRef"
+    Pizza:
+      type: object
+      properties:
+        pizzaSize:
+          type: number
+      allOf:
+        - $ref: '#/components/schemas/Entity'
+    Pasta:
+      type: object
+      properties:
+        vendor:
+          type: string
+      allOf:
+        - $ref: '#/components/schemas/Entity'
+    PizzaSpeziale:
+      type: object
+      properties:
+        toppings:
+          type: string
+      allOf:
+        - $ref: '#/components/schemas/Pizza'
+    FruitType:
+      type: string
+      enum: [APPLE, BANANA]
+    Fruit:
+      type: object
+      properties:
+        fruitType:
+          $ref: "#/components/schemas/FruitType"
+          description: "test"
+      required:
+        - fruitType
+      oneOf:
+        - $ref: '#/components/schemas/Apple'
+        - $ref: '#/components/schemas/Banana'
+      discriminator:
+        propertyName: fruitType
+        mapping:
+          APPLE: '#/components/schemas/Apple'
+          BANANA: '#/components/schemas/Banana'
+    Apple:
+      type: object
+      required:
+        - seeds
+      properties:
+        seeds:
+          type: integer
+    Banana:
+      type: object
+      required:
+        - length
+      properties:
+        length:
+          type: integer
+    Animal:
+      oneOf:
+        - $ref: '#/components/schemas/Dog'
+        - $ref: '#/components/schemas/Cat'
+    Cat:
+      type: object
+      properties:
+        declawed:
+          type: boolean
+    Dog:
+      type: object
+      properties:
+        bark:
+          type: boolean
+
+  requestBodies:
+    Foo:
+      description: The Foo to be created
+      content:
+        application/json;charset=utf-8:
+          schema:
+            $ref: '#/components/schemas/Foo'
+
+  responses:
+    '204':
+      description: Deleted
+      content: { }
+    201Foo:
+      description: Error
+      content:
+        application/json:
+          schema:
+            $ref: '#/components/schemas/FooRefOrValue'
+    200FooArray:
+      description: Success
+      content:
+        application/json;charset=utf-8:
+          schema:
+            type: array
+            items:
+              $ref: '#/components/schemas/FooRefOrValue'