DRAFT: Jaxrs-spec: Resolve @JsonTypeName with the mapping key of the discriminator in the child models when OpenAPI specification uses OneOf for polymorphism

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

@@ -26,6 +26,7 @@
 import org.openapitools.codegen.meta.features.DocumentationFeature;
 import org.openapitools.codegen.meta.features.SecurityFeature;
 import org.openapitools.codegen.model.ModelMap;
+import org.openapitools.codegen.model.ModelsMap;
 import org.openapitools.codegen.model.OperationsMap;
 
 import java.io.File;
@@ -327,11 +328,37 @@ public void postProcessModelProperty(CodegenModel model, CodegenProperty propert
         }
     }
 
+    @Override
+    public ModelsMap postProcessModels(ModelsMap objs) {
+        return super.postProcessModels(objs);
+    }
+
     @Override
     public OperationsMap postProcessOperationsWithModels(OperationsMap objs, List<ModelMap> allModels) {
         objs = super.postProcessOperationsWithModels(objs, allModels);
         removeImport(objs, "java.util.List");
         return objs;
     }
 
+    @Override
+    public Map<String, ModelsMap> postProcessAllModels(Map<String, ModelsMap> objs) {
+        Map<String, ModelsMap> result = super.postProcessAllModels(objs);
+        for (ModelsMap modelsMap : result.values()) {
+            for (ModelMap modelMap : modelsMap.getModels()) {
+                CodegenModel model = modelMap.getModel();
+                if (model.parentModel != null) {
+                    CodegenDiscriminator discriminator = model.parentModel.getDiscriminator();
+                    if (discriminator != null) {
+                        for (CodegenDiscriminator.MappedModel mappedModel : discriminator.getMappedModels()) {
+                            if (mappedModel.getModelName().equals(model.name)) {
+                                model.getVendorExtensions().put("x-discriminator-value", mappedModel.getMappingName());
+                                break;
+                            }
+                        }
+                    }
+                }
+            }
+        }
+        return result;
+    }
 }

modules/openapi-generator/src/main/resources/JavaJaxRS/spec/pojo.mustache

@@ -38,7 +38,7 @@ import {{javaxPackage}}.xml.bind.annotation.XmlEnumValue;
 @Schema({{#title}}title="{{{.}}}", {{/title}}{{#description}}description="{{{.}}}"{{/description}}{{^description}}description=""{{/description}}){{/useSwaggerV3Annotations}}{{#useMicroProfileOpenAPIAnnotations}}
 @org.eclipse.microprofile.openapi.annotations.media.Schema({{#title}}title="{{{.}}}", {{/title}}{{#description}}description="{{{.}}}"{{/description}}{{^description}}description=""{{/description}}){{/useMicroProfileOpenAPIAnnotations}}
 {{#jackson}}
-@JsonTypeName("{{name}}")
+@JsonTypeName("{{#vendorExtensions.x-discriminator-value}}{{{vendorExtensions.x-discriminator-value}}}{{/vendorExtensions.x-discriminator-value}}{{^vendorExtensions.x-discriminator-value}}{{name}}{{/vendorExtensions.x-discriminator-value}}")
 {{#additionalProperties}}
 @JsonFormat(shape=JsonFormat.Shape.OBJECT)
 {{/additionalProperties}}

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

@@ -1237,4 +1237,35 @@ public void disableGenerateJsonCreator() throws Exception {
         assertFileNotContains(files.get("RequiredProperties.java").toPath(), "@JsonCreator");
     }
 
+    @Test
+    public void testDiscriminatorMappingUsedInJsonTypeName() throws Exception {
+        File output = Files.createTempDirectory("test").toFile().getCanonicalFile();
+        output.deleteOnExit();
+
+        OpenAPI openAPI = new OpenAPIParser()
+                .readLocation("src/test/resources/3_0/jaxrs/pestore-with-discriminator.yaml", null, new ParseOptions()).getOpenAPI();
+
+        codegen.setOutputDir(output.getAbsolutePath());
+
+        ClientOptInput input = new ClientOptInput()
+                .openAPI(openAPI)
+                .config(codegen);
+
+        DefaultGenerator generator = new DefaultGenerator();
+        Map<String, File> files = generator.opts(input).generate().stream()
+                .collect(Collectors.toMap(File::getName, Function.identity()));
+
+        // Parent model uses its own name
+        JavaFileAssert.assertThat(files.get("PetRequest.java"))
+                .fileContains("@JsonTypeName(\"PetRequest\")");
+
+        // Child models must use the discriminator mapping value (e.g. "CAT"), not the class name (e.g. "CatRequest")
+        JavaFileAssert.assertThat(files.get("CatRequest.java"))
+                .fileContains("@JsonTypeName(\"CAT\")")
+                .fileDoesNotContain("@JsonTypeName(\"CatRequest\")");
+
+        JavaFileAssert.assertThat(files.get("DogRequest.java"))
+                .fileContains("@JsonTypeName(\"DOG\")")
+                .fileDoesNotContain("@JsonTypeName(\"DogRequest\")");
+    }
 }

modules/openapi-generator/src/test/resources/3_0/jaxrs/pestore-with-discriminator.yaml

@@ -0,0 +1,69 @@
+openapi: 3.0.0
+servers:
+  - url: 'http://petstore.swagger.io/v2'
+info:
+  description: >-
+    This is a sample server Petstore server that uses polymorphism and inheritance with a discriminator.
+  version: 1.0.0
+  title: OpenAPI Petstore
+  license:
+    name: Apache-2.0
+    url: 'https://www.apache.org/licenses/LICENSE-2.0.html'
+
+tags:
+  - name: pet
+    description: Everything about your Pets
+
+paths:
+  /pets:
+    post:
+      operationId: createPet
+      security: []
+      tags: [ pet ]
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/PetRequest'
+      responses:
+        '201':
+          description: Pet created successfully
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/PetRequest'
+
+components:
+  schemas:
+    PetRequest:
+      type: object
+      required:
+        - petType
+      properties:
+        petType:
+          type: string
+        name:
+          type: string
+      oneOf:
+        - $ref: '#/components/schemas/CatRequest'
+        - $ref: '#/components/schemas/DogRequest'
+      discriminator:
+        propertyName: petType
+        mapping:
+          CAT: '#/components/schemas/CatRequest'
+          DOG: '#/components/schemas/DogRequest'
+    CatRequest:
+      allOf:
+        - $ref: '#/components/schemas/PetRequest'
+        - type: object
+          properties:
+            indoor:
+              type: boolean
+    DogRequest:
+      allOf:
+        - $ref: '#/components/schemas/PetRequest'
+        - type: object
+          properties:
+            bark:
+              type: string