fix: allow openApiNullable with useJackson3

Author: sonallux

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

@@ -306,7 +306,7 @@ public SpringCodegen() {
         cliOptions.add(CliOption.newBoolean(USE_SPRING_BOOT4,
                 "Generate code and provide dependencies for use with Spring Boot 4.x. (Use jakarta instead of javax in imports). Enabling this option will also enable `useJakartaEe`.",
                 useSpringBoot4));
-        cliOptions.add(CliOption.newBoolean(USE_JACKSON_3, "Set it in order to use jackson 3 dependencies (only allowed when `" + USE_SPRING_BOOT4 + "` is set and incompatible with `"+OPENAPI_NULLABLE+"`).", useJackson3));
+        cliOptions.add(CliOption.newBoolean(USE_JACKSON_3, "Set it in order to use jackson 3 dependencies (only allowed when `" + USE_SPRING_BOOT4 + "` is set).", useJackson3));
         cliOptions.add(new CliOption(INCLUDE_HTTP_REQUEST_CONTEXT,
                 "Whether to include HttpServletRequest (blocking) or ServerWebExchange (reactive) as additional parameter in generated methods. Defaults to 'true' for reactive and 'false' for blocking.",
                 SchemaTypeUtil.BOOLEAN_TYPE).defaultValue("true (reactive) / false (blocking)"));
@@ -535,9 +535,6 @@ public void processOpts() {
         if(isUseJackson3() && !isUseSpringBoot4()){
             throw new IllegalArgumentException("useJackson3 is only available with Spring Boot >= 4");
         }
-        if(isUseJackson3() && isOpenApiNullable()){
-            throw new IllegalArgumentException("openApiNullable cannot be set with useJackson3");
-        }
         if(this.useJackson3){
             this.applyJackson3Package();
         } else {

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

@@ -6512,31 +6512,6 @@ public void shouldRefuseJackson3WithoutSpringboot4() throws IOException {
                 .isThrownBy(generator::generate);
     }
 
-    @Test
-    public void shouldRefuseOpenApiNullableWithJackson3() throws IOException {
-        File output = Files.createTempDirectory("test").toFile().getCanonicalFile();
-        output.deleteOnExit();
-
-        final OpenAPI openAPI = TestUtils.parseFlattenSpec("src/test/resources/3_0/petstore-echo.yaml");
-        final SpringCodegen codegen = new SpringCodegen();
-        codegen.setOpenAPI(openAPI);
-        codegen.setOutputDir(output.getAbsolutePath());
-
-        codegen.additionalProperties().put(SpringCodegen.USE_SPRING_BOOT4, "true");
-        codegen.additionalProperties().put(SpringCodegen.USE_JACKSON_3, "true");
-        codegen.additionalProperties().put(SpringCodegen.OPENAPI_NULLABLE, "true");
-
-        ClientOptInput input = new ClientOptInput();
-        input.openAPI(openAPI);
-        input.config(codegen);
-
-        Generator generator = new DefaultGenerator()
-                .opts(input);
-
-        Assertions.assertThatExceptionOfType(IllegalArgumentException.class)
-                .isThrownBy(generator::generate);
-    }
-
     @Test
     public void shouldImportJackson2JsonDeserializeForUniqueItemsWhenJackson3NotSet() throws IOException {
         File output = Files.createTempDirectory("test").toFile().getCanonicalFile();