[Java] [Spring] Use deduction configOptions for oneOfInterfaces (#20919)

* fix(java): x-discriminator-value should not produce @JsonTypeName

* fix(java): Remove unused getDiscriminatorValue()

* build at Fednot

* build at Fednot

* build at Fednot: skip sonar

* scm for release at fednot

* build fednot not 7.5.0-FEDNOT-SNAPSHOT

* build fednot not 7.5.0-FEDNOT-SNAPSHOT

* test all vars

* rollback custom pom.xml

* commit master

* commit test

* Samples for deduction

* add files  for deduction

* small improvements

* Merge changes from martin-mfg
Merge master

* Merge changes from martin-mfg
Merge master

* Merge changes from martin-mfg
Add comment to force rebuild

* Merge master

* regenerate doc

* regenerate client

* regenerate client

---------

Co-authored-by: Jean-Paul Finne <jean-paul.finne@fednot.be>
Co-authored-by: martin-mfg <2026226+martin-mfg@users.noreply.github.com>

Author: 3 people

.github/workflows/samples-spring-jdk17.yaml

@@ -11,6 +11,7 @@ on:
       - samples/server/petstore/springboot-file-delegate-optional
       - samples/server/petstore/springboot-petstore-with-api-response-examples
       - samples/server/petstore/spring-boot-oneof-sealed
+      - samples/openapi3/server/petstore/spring-boot-oneof-interface
   pull_request:
     paths:
       - samples/openapi3/client/petstore/spring-cloud-3-with-optional
@@ -21,6 +22,7 @@ on:
       - samples/server/petstore/springboot-file-delegate-optional
       - samples/server/petstore/springboot-petstore-with-api-response-examples
       - samples/server/petstore/spring-boot-oneof-sealed
+      - samples/openapi3/server/petstore/spring-boot-oneof-interface
 jobs:
   build:
     name: Build Java Spring (JDK17)
@@ -39,6 +41,7 @@ jobs:
           - samples/server/petstore/springboot-file-delegate-optional
           - samples/server/petstore/springboot-petstore-with-api-response-examples
           - samples/server/petstore/spring-boot-oneof-sealed
+          - samples/openapi3/server/petstore/spring-boot-oneof-interface
     steps:
       - uses: actions/checkout@v5
       - uses: actions/setup-java@v5

.github/workflows/samples-spring.yaml

@@ -60,6 +60,7 @@ jobs:
           - samples/server/petstore/springboot-spring-provide-args
           - samples/server/petstore/springboot-useoptional
           - samples/server/petstore/springboot-virtualan
+          - samples/openapi3/server/petstore/spring-boot-oneof-interface
     steps:
       - uses: actions/checkout@v5
       - uses: actions/setup-java@v5

bin/configs/spring-boot-oneof-interface.yaml

@@ -0,0 +1,12 @@
+generatorName: spring
+outputDir: samples/openapi3/server/petstore/spring-boot-oneof-interface
+inputSpec: modules/openapi-generator/src/test/resources/3_0/oneof_polymorphism_and_inheritance.yaml
+templateDir: modules/openapi-generator/src/main/resources/JavaSpring
+additionalProperties:
+  groupId: org.openapitools.openapi3
+  documentationProvider: springdoc
+  artifactId: springboot-oneof
+  snapshotVersion: "true"
+  hideGenerationTimestamp: "true"
+  useOneOfInterfaces: "true"
+  useDeductionForOneOfInterfaces: "true"

docs/generators/java-camel.md

@@ -99,6 +99,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |title|server title name or client service name| |OpenAPI Spring|
 |unhandledException|Declare operation methods to throw a generic exception and allow unhandled exceptions (useful for Spring `@ControllerAdvice` directives).| |false|
 |useBeanValidation|Use BeanValidation API annotations| |true|
+|useDeductionForOneOfInterfaces|whether to use deduction for generated oneOf interfaces| |false|
 |useEnumCaseInsensitive|Use `equalsIgnoreCase` when String for enum comparison| |false|
 |useFeignClientContextId|Whether to generate Feign client with contextId parameter.| |true|
 |useFeignClientUrl|Whether to generate Feign client with url parameter.| |true|

docs/generators/spring.md

@@ -92,6 +92,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |title|server title name or client service name| |OpenAPI Spring|
 |unhandledException|Declare operation methods to throw a generic exception and allow unhandled exceptions (useful for Spring `@ControllerAdvice` directives).| |false|
 |useBeanValidation|Use BeanValidation API annotations| |true|
+|useDeductionForOneOfInterfaces|whether to use deduction for generated oneOf interfaces| |false|
 |useEnumCaseInsensitive|Use `equalsIgnoreCase` when String for enum comparison| |false|
 |useFeignClientContextId|Whether to generate Feign client with contextId parameter.| |true|
 |useFeignClientUrl|Whether to generate Feign client with url parameter.| |true|

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

@@ -99,6 +99,7 @@ public class SpringCodegen extends AbstractJavaCodegen
     public static final String USE_SEALED = "useSealed";
     public static final String OPTIONAL_ACCEPT_NULLABLE = "optionalAcceptNullable";
     public static final String USE_SPRING_BUILT_IN_VALIDATION = "useSpringBuiltInValidation";
+    public static final String USE_DEDUCTION_FOR_ONE_OF_INTERFACES = "useDeductionForOneOfInterfaces";
 
     @Getter
     public enum RequestMappingMode {
@@ -159,6 +160,8 @@ public enum RequestMappingMode {
     protected boolean optionalAcceptNullable = true;
     @Getter @Setter
     protected boolean useSpringBuiltInValidation = false;
+    @Getter @Setter
+    protected boolean useDeductionForOneOfInterfaces = false;
 
     public SpringCodegen() {
         super();
@@ -282,6 +285,7 @@ public SpringCodegen() {
                 "Use `ofNullable` instead of just `of` to accept null values when using Optional.",
                 optionalAcceptNullable));
 
+        cliOptions.add(CliOption.newBoolean(USE_DEDUCTION_FOR_ONE_OF_INTERFACES, "whether to use deduction for generated oneOf interfaces", useDeductionForOneOfInterfaces));
         supportedLibraries.put(SPRING_BOOT, "Spring-boot Server application.");
         supportedLibraries.put(SPRING_CLOUD_LIBRARY,
                 "Spring-Cloud-Feign client with Spring-Boot auto-configured settings.");
@@ -449,6 +453,7 @@ public void processOpts() {
         }
         convertPropertyToBooleanAndWriteBack(OPTIONAL_ACCEPT_NULLABLE, this::setOptionalAcceptNullable);
         convertPropertyToBooleanAndWriteBack(USE_SPRING_BUILT_IN_VALIDATION, this::setUseSpringBuiltInValidation);
+        convertPropertyToBooleanAndWriteBack(USE_DEDUCTION_FOR_ONE_OF_INTERFACES, this::setUseDeductionForOneOfInterfaces);
 
         additionalProperties.put("springHttpStatus", new SpringHttpStatusLambda());
 

modules/openapi-generator/src/main/resources/JavaSpring/oneof_interface.mustache

@@ -6,6 +6,14 @@
 {{#discriminator}}
 {{>typeInfoAnnotation}}
 
+{{/discriminator}}{{^discriminator}}{{#useDeductionForOneOfInterfaces}}
+@JsonTypeInfo(use = JsonTypeInfo.Id.DEDUCTION)
+@JsonSubTypes({
+    {{#interfaceModels}}
+    @JsonSubTypes.Type(value = {{classname}}.class){{^-last}}, {{/-last}}
+    {{/interfaceModels}}
+})
+{{/useDeductionForOneOfInterfaces}}
 {{/discriminator}}
 {{>generatedAnnotation}}
 

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

@@ -1764,10 +1764,13 @@ public void testOneOfAndAllOf() throws IOException {
         generator.setGeneratorPropertyDefault(CodegenConstants.LEGACY_DISCRIMINATOR_BEHAVIOR, "false");
 
         codegen.setUseOneOfInterfaces(true);
+        codegen.setUseDeductionForOneOfInterfaces(true);
         codegen.setLegacyDiscriminatorBehavior(false);
 
         generator.opts(input).generate();
 
+        // test deduction
+        assertFileContains(Paths.get(outputPath + "/src/main/java/org/openapitools/model/Animal.java"), "@JsonTypeInfo(use = JsonTypeInfo.Id.DEDUCTION)", "@JsonSubTypes.Type(value = Dog.class),", "@JsonSubTypes.Type(value = Cat.class)");
         assertFileContains(Paths.get(outputPath + "/src/main/java/org/openapitools/model/Foo.java"), "public class Foo extends Entity implements FooRefOrValue");
         assertFileContains(Paths.get(outputPath + "/src/main/java/org/openapitools/model/FooRef.java"), "public class FooRef extends EntityRef implements FooRefOrValue");
         assertFileContains(Paths.get(outputPath + "/src/main/java/org/openapitools/model/FooRefOrValue.java"), "public interface FooRefOrValue");

modules/openapi-generator/src/test/resources/3_0/oneof_polymorphism_and_inheritance.yaml

@@ -209,6 +209,20 @@ components:
       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:

samples/client/echo_api/java/okhttp-gson-user-defined-templates/README.md

@@ -0,0 +1,184 @@
+# openapi-java-client
+
+OpenAPI Petstore
+- API version: 1.0.0
+  - Generator version: 7.6.0-SNAPSHOT
+
+This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+
+
+*Automatically generated by the [OpenAPI Generator](https://openapi-generator.tech)*
+
+
+## Requirements
+
+Building the API client library requires:
+1. Java 1.8+
+2. Maven (3.8.3+)/Gradle (7.2+)
+
+## Installation
+
+To install the API client library to your local Maven repository, simply execute:
+
+```shell
+mvn clean install
+```
+
+To deploy it to a remote Maven repository instead, configure the settings of the repository and execute:
+
+```shell
+mvn clean deploy
+```
+
+Refer to the [OSSRH Guide](http://central.sonatype.org/pages/ossrh-guide.html) for more information.
+
+### Maven users
+
+Add this dependency to your project's POM:
+
+```xml
+<dependency>
+  <groupId>org.openapitools</groupId>
+  <artifactId>openapi-java-client</artifactId>
+  <version>1.0.0</version>
+  <scope>compile</scope>
+</dependency>
+```
+
+### Gradle users
+
+Add this dependency to your project's build file:
+
+```groovy
+  repositories {
+    mavenCentral()     // Needed if the 'openapi-java-client' jar has been published to maven central.
+    mavenLocal()       // Needed if the 'openapi-java-client' jar has been published to the local maven repo.
+  }
+
+  dependencies {
+     implementation "org.openapitools:openapi-java-client:1.0.0"
+  }
+```
+
+### Others
+
+At first generate the JAR by executing:
+
+```shell
+mvn clean package
+```
+
+Then manually install the following JARs:
+
+* `target/openapi-java-client-1.0.0.jar`
+* `target/lib/*.jar`
+
+## Getting Started
+
+Please follow the [installation](#installation) instruction and execute the following Java code:
+
+```java
+
+// Import classes:
+import org.openapitools.client.ApiClient;
+import org.openapitools.client.ApiException;
+import org.openapitools.client.Configuration;
+import org.openapitools.client.auth.*;
+import org.openapitools.client.models.*;
+import org.openapitools.client.api.PetApi;
+
+public class Example {
+  public static void main(String[] args) {
+    ApiClient defaultClient = Configuration.getDefaultApiClient();
+    defaultClient.setBasePath("http://petstore.swagger.io/v2");
+    
+    // Configure OAuth2 access token for authorization: petstore_auth
+    OAuth petstore_auth = (OAuth) defaultClient.getAuthentication("petstore_auth");
+    petstore_auth.setAccessToken("YOUR ACCESS TOKEN");
+
+    PetApi apiInstance = new PetApi(defaultClient);
+    Pet pet = new Pet(); // Pet | Pet object that needs to be added to the store
+    try {
+      Pet result = apiInstance.addPet(pet);
+      System.out.println(result);
+    } catch (ApiException e) {
+      System.err.println("Exception when calling PetApi#addPet");
+      System.err.println("Status code: " + e.getCode());
+      System.err.println("Reason: " + e.getResponseBody());
+      System.err.println("Response headers: " + e.getResponseHeaders());
+      e.printStackTrace();
+    }
+  }
+}
+
+```
+
+## Documentation for API Endpoints
+
+All URIs are relative to *http://petstore.swagger.io/v2*
+
+Class | Method | HTTP request | Description
+------------ | ------------- | ------------- | -------------
+*PetApi* | [**addPet**](docs/PetApi.md#addPet) | **POST** /pet | Add a new pet to the store
+*PetApi* | [**deletePet**](docs/PetApi.md#deletePet) | **DELETE** /pet/{petId} | Deletes a pet
+*PetApi* | [**findPetsByStatus**](docs/PetApi.md#findPetsByStatus) | **GET** /pet/findByStatus | Finds Pets by status
+*PetApi* | [**findPetsByTags**](docs/PetApi.md#findPetsByTags) | **GET** /pet/findByTags | Finds Pets by tags
+*PetApi* | [**getPetById**](docs/PetApi.md#getPetById) | **GET** /pet/{petId} | Find pet by ID
+*PetApi* | [**updatePet**](docs/PetApi.md#updatePet) | **PUT** /pet | Update an existing pet
+*PetApi* | [**updatePetWithForm**](docs/PetApi.md#updatePetWithForm) | **POST** /pet/{petId} | Updates a pet in the store with form data
+*PetApi* | [**uploadFile**](docs/PetApi.md#uploadFile) | **POST** /pet/{petId}/uploadImage | uploads an image
+*StoreApi* | [**deleteOrder**](docs/StoreApi.md#deleteOrder) | **DELETE** /store/order/{orderId} | Delete purchase order by ID
+*StoreApi* | [**getInventory**](docs/StoreApi.md#getInventory) | **GET** /store/inventory | Returns pet inventories by status
+*StoreApi* | [**getOrderById**](docs/StoreApi.md#getOrderById) | **GET** /store/order/{orderId} | Find purchase order by ID
+*StoreApi* | [**placeOrder**](docs/StoreApi.md#placeOrder) | **POST** /store/order | Place an order for a pet
+*UserApi* | [**createUser**](docs/UserApi.md#createUser) | **POST** /user | Create user
+*UserApi* | [**createUsersWithArrayInput**](docs/UserApi.md#createUsersWithArrayInput) | **POST** /user/createWithArray | Creates list of users with given input array
+*UserApi* | [**createUsersWithListInput**](docs/UserApi.md#createUsersWithListInput) | **POST** /user/createWithList | Creates list of users with given input array
+*UserApi* | [**deleteUser**](docs/UserApi.md#deleteUser) | **DELETE** /user/{username} | Delete user
+*UserApi* | [**getUserByName**](docs/UserApi.md#getUserByName) | **GET** /user/{username} | Get user by user name
+*UserApi* | [**loginUser**](docs/UserApi.md#loginUser) | **GET** /user/login | Logs user into the system
+*UserApi* | [**logoutUser**](docs/UserApi.md#logoutUser) | **GET** /user/logout | Logs out current logged in user session
+*UserApi* | [**updateUser**](docs/UserApi.md#updateUser) | **PUT** /user/{username} | Updated user
+
+
+## Documentation for Models
+
+ - [Category](docs/Category.md)
+ - [ModelApiResponse](docs/ModelApiResponse.md)
+ - [Order](docs/Order.md)
+ - [Pet](docs/Pet.md)
+ - [Tag](docs/Tag.md)
+ - [User](docs/User.md)
+
+
+<a id="documentation-for-authorization"></a>
+## Documentation for Authorization
+
+
+Authentication schemes defined for the API:
+<a id="petstore_auth"></a>
+### petstore_auth
+
+- **Type**: OAuth
+- **Flow**: implicit
+- **Authorization URL**: http://petstore.swagger.io/api/oauth/dialog
+- **Scopes**: 
+  - write:pets: modify pets in your account
+  - read:pets: read your pets
+
+<a id="api_key"></a>
+### api_key
+
+- **Type**: API key
+- **API key parameter name**: api_key
+- **Location**: HTTP header
+
+
+## Recommendation
+
+It's recommended to create an instance of `ApiClient` per thread in a multithreaded environment to avoid any potential issues.
+
+## Author
+
+
+