Use deduction for interface on java generators

Author: jpfinne

docs/generators/java.md

@@ -95,6 +95,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |testOutput|Set output folder for models and APIs tests| |${project.build.directory}/generated-test-sources/openapi|
 |useAbstractionForFiles|Use alternative types instead of java.io.File to allow passing bytes without a file on disk. Available on resttemplate, webclient, restclient, libraries| |false|
 |useBeanValidation|Use BeanValidation API annotations| |false|
+|useDeductionForOneOfInterfaces|whether to use deduction for generated oneOf interfaces| |false|
 |useEnumCaseInsensitive|Use `equalsIgnoreCase` when String for enum comparison| |false|
 |useGzipFeature|Send gzip-encoded requests| |false|
 |useJackson3|Use Jackson 3 instead of Jackson 2. Supported for 'native' and 'apache-httpclient' libraries (requires Java 17+) and for Spring 'resttemplate', 'webclient', and 'restclient' libraries (require useSpringBoot4=true).| |false|

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

@@ -118,6 +118,7 @@ public abstract class AbstractJavaCodegen extends DefaultCodegen implements Code
     public static final String DEFAULT_TEST_FOLDER = "${project.build.directory}/generated-test-sources/openapi";
     public static final String GENERATE_CONSTRUCTOR_WITH_ALL_ARGS = "generateConstructorWithAllArgs";
     public static final String GENERATE_BUILDERS = "generateBuilders";
+    public static final String USE_DEDUCTION_FOR_ONE_OF_INTERFACES = "useDeductionForOneOfInterfaces";
 
     @Getter @Setter
     protected String dateLibrary = "java8";
@@ -225,6 +226,8 @@ protected enum ENUM_PROPERTY_NAMING_TYPE {MACRO_CASE, legacy, original}
     @Setter
     protected boolean useJspecify;
     protected JSpecifyNullableLambda jSpecifyNullableLambda;
+    @Getter @Setter
+    protected boolean useDeductionForOneOfInterfaces = false;
 
     private Map<String, String> schemaKeyToModelNameCache = new HashMap<>();
 
@@ -608,6 +611,7 @@ public void processOpts() {
         convertPropertyToBooleanAndWriteBack(USE_ONE_OF_INTERFACES, this::setUseOneOfInterfaces);
         convertPropertyToStringAndWriteBack(CodegenConstants.ENUM_PROPERTY_NAMING, this::setEnumPropertyNaming);
         convertPropertyToBooleanAndWriteBack(USE_JSPECIFY, this::setUseJspecify);
+        convertPropertyToBooleanAndWriteBack(USE_DEDUCTION_FOR_ONE_OF_INTERFACES, this::setUseDeductionForOneOfInterfaces);
 
         if (!StringUtils.isEmpty(parentGroupId) && !StringUtils.isEmpty(parentArtifactId) && !StringUtils.isEmpty(parentVersion)) {
             additionalProperties.put("parentOverridden", true);

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

@@ -285,6 +285,7 @@ public JavaClientCodegen() {
         cliOptions.add(CliOption.newBoolean(USE_SEALED_ONE_OF_INTERFACES, "Generate the oneOf interfaces as sealed interfaces. Only supported for WebClient and RestClient.", this.useSealedOneOfInterfaces));
         cliOptions.add(CliOption.newBoolean(USE_UNARY_INTERCEPTOR, "If true it will generate ResponseInterceptors using a UnaryOperator. This can be usefull for manipulating the request before it gets passed, for example doing your own decryption", this.useUnaryInterceptor));
         cliOptions.add(CliOption.newBoolean(USE_JSPECIFY, "Use Jspecify for null checks. Only supported for " + JSPECIFY_SUPPORTED_LIBRARIES, useJspecify));
+        cliOptions.add(CliOption.newBoolean(USE_DEDUCTION_FOR_ONE_OF_INTERFACES, "whether to use deduction for generated oneOf interfaces", useDeductionForOneOfInterfaces));
 
         supportedLibraries.put(JERSEY2, "HTTP client: Jersey client 2.25.1. JSON processing: Jackson 2.17.1");
         supportedLibraries.put(JERSEY3, "HTTP client: Jersey client 3.1.1. JSON processing: Jackson 2.17.1");

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

@@ -110,7 +110,6 @@ 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";
     public static final String SPRING_API_VERSION = "springApiVersion";
     public static final String USE_JACKSON_3 = "useJackson3";
     public static final String JACKSON2_PACKAGE = "com.fasterxml.jackson";
@@ -187,8 +186,6 @@ public enum RequestMappingMode {
     @Getter @Setter
     protected boolean useSpringBuiltInValidation = false;
     @Getter @Setter
-    protected boolean useDeductionForOneOfInterfaces = false;
-    @Getter @Setter
     protected boolean useJackson3 = false;
     @Getter @Setter
     protected boolean additionalNotNullAnnotations = false;
@@ -557,7 +554,6 @@ 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/Java/deductionAnnotation.mustache

@@ -0,0 +1,12 @@
+{{^discriminator}}
+{{#jackson}}
+{{#useDeductionForOneOfInterfaces}}
+    @JsonTypeInfo(use = JsonTypeInfo.Id.DEDUCTION)
+    @JsonSubTypes({
+    {{#interfaceModels}}
+        @JsonSubTypes.Type(value = {{classname}}.class){{^-last}}, {{/-last}}
+    {{/interfaceModels}}
+    })
+{{/useDeductionForOneOfInterfaces}}
+{{/jackson}}
+{{/discriminator}}

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

@@ -1,4 +1,4 @@
-{{>additionalOneOfTypeAnnotations}}{{>generatedAnnotation}}{{>typeInfoAnnotation}}{{>xmlAnnotation}}
+{{>additionalOneOfTypeAnnotations}}{{>generatedAnnotation}}{{>typeInfoAnnotation}}{{>deductionAnnotation}}{{>xmlAnnotation}}
 {{#vendorExtensions.x-class-extra-annotation}}
 {{{vendorExtensions.x-class-extra-annotation}}}
 {{/vendorExtensions.x-class-extra-annotation}}

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

@@ -4452,4 +4452,18 @@ void oneOf_issue_912() {
                 .recursivelyContainsWithNameAndAttributes("JsonSubTypes.Type", Map.of("value", "Source.class", "name", "\"source\""));
     }
 
+    @Test
+    public void testUseDeductionForOneInterfaces() {
+        final Map<String, File> files = generateFromContract("src/test/resources/3_1/oneof_polymorphism_and_inheritance.yaml", RESTCLIENT,
+                Map.of(USE_ONE_OF_INTERFACES, "true", USE_DEDUCTION_FOR_ONE_OF_INTERFACES, "true"));
+        JavaFileAssert.assertThat(files.get("Animal.java")).fileContains("@JsonSubTypes")
+                .isInterface()
+                .assertTypeAnnotations().containsWithName("JsonSubTypes")
+                .recursivelyContainsWithNameAndAttributes("JsonSubTypes.Type", Map.of("value", "Dog.class"))
+                .recursivelyContainsWithNameAndAttributes("JsonSubTypes.Type", Map.of("value", "Cat.class"))
+                .containsWithNameAndAttributes("JsonTypeInfo", Map.of("use", "JsonTypeInfo.Id.DEDUCTION"));
+
+    }
+
+
 }