fix(kotlin-spring): use Jackson 3 annotation package in model imports

When useJackson3=true, generated model source files still imported from
com.fasterxml.jackson.annotation (Jackson 2). The importMapping in
KotlinSpringServerCodegen was hardcoded to the Jackson 2 package.

Now derives the annotation package from the useJackson3 flag, consistent
with how build files already handled it. Also fixes the hardcoded
YAMLMapper import in homeController.mustache.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: yonatankarp

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

@@ -492,15 +492,16 @@ public void processOpts() {
         importMapping.put("ApiModelProperty", "io.swagger.annotations.ApiModelProperty");
 
         // Jackson import mappings
-        importMapping.put("JsonValue", "com.fasterxml.jackson.annotation.JsonValue");
-        importMapping.put("JsonCreator", "com.fasterxml.jackson.annotation.JsonCreator");
-        importMapping.put("JsonProperty", "com.fasterxml.jackson.annotation.JsonProperty");
-        importMapping.put("JsonSubTypes", "com.fasterxml.jackson.annotation.JsonSubTypes");
-        importMapping.put("JsonTypeInfo", "com.fasterxml.jackson.annotation.JsonTypeInfo");
-        importMapping.put("JsonIgnoreProperties", "com.fasterxml.jackson.annotation.JsonIgnoreProperties");
+        String jacksonAnnotationPkg = isUseJackson3() ? JACKSON3_PACKAGE : JACKSON2_PACKAGE;
+        importMapping.put("JsonValue", jacksonAnnotationPkg + ".annotation.JsonValue");
+        importMapping.put("JsonCreator", jacksonAnnotationPkg + ".annotation.JsonCreator");
+        importMapping.put("JsonProperty", jacksonAnnotationPkg + ".annotation.JsonProperty");
+        importMapping.put("JsonSubTypes", jacksonAnnotationPkg + ".annotation.JsonSubTypes");
+        importMapping.put("JsonTypeInfo", jacksonAnnotationPkg + ".annotation.JsonTypeInfo");
+        importMapping.put("JsonIgnoreProperties", jacksonAnnotationPkg + ".annotation.JsonIgnoreProperties");
         // import JsonCreator if JsonProperty is imported
         // used later in recursive import in postProcessingModels
-        importMapping.put("com.fasterxml.jackson.annotation.JsonProperty", "com.fasterxml.jackson.annotation.JsonCreator");
+        importMapping.put(jacksonAnnotationPkg + ".annotation.JsonProperty", jacksonAnnotationPkg + ".annotation.JsonCreator");
 
         if (isUseJackson3()) {
             // Override databind imports for Jackson 3

modules/openapi-generator/src/main/resources/kotlin-spring/homeController.mustache

@@ -4,7 +4,7 @@ import org.springframework.context.annotation.Bean
 import org.springframework.stereotype.Controller
 import org.springframework.web.bind.annotation.RequestMapping
 {{#sourceDocumentationProvider}}
-import com.fasterxml.jackson.dataformat.yaml.YAMLMapper
+import {{jacksonPackage}}.dataformat.yaml.YAMLMapper
 import org.springframework.beans.factory.annotation.Value
 import org.springframework.core.io.Resource
 import org.springframework.util.StreamUtils

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

@@ -4825,6 +4825,42 @@ public void shouldGenerateSpringBoot4PomWithJackson3Deps() throws IOException {
         assertFileNotContains(pomPath, "com.fasterxml.jackson.module");
     }
 
+    @Test
+    public void shouldGenerateJackson3AnnotationImportsInModels() throws IOException {
+        File output = Files.createTempDirectory("test").toFile().getCanonicalFile();
+        output.deleteOnExit();
+        String outputPath = output.getAbsolutePath().replace('\\', '/');
+
+        final OpenAPI openAPI = TestUtils.parseFlattenSpec("src/test/resources/3_0/petstore.yaml");
+        final KotlinSpringServerCodegen codegen = new KotlinSpringServerCodegen();
+        codegen.setOpenAPI(openAPI);
+        codegen.setOutputDir(output.getAbsolutePath());
+
+        codegen.additionalProperties().put(KotlinSpringServerCodegen.USE_SPRING_BOOT4, "true");
+        codegen.additionalProperties().put(AbstractKotlinCodegen.USE_JACKSON_3, "true");
+        codegen.additionalProperties().put(DOCUMENTATION_PROVIDER, DocumentationProvider.NONE.toCliOptValue());
+        codegen.additionalProperties().put(ANNOTATION_LIBRARY, AnnotationLibrary.NONE.toCliOptValue());
+
+        ClientOptInput input = new ClientOptInput();
+        input.openAPI(openAPI);
+        input.config(codegen);
+
+        DefaultGenerator generator = new DefaultGenerator();
+        generator.setGenerateMetadata(false);
+        generator.opts(input).generate();
+
+        // Model files must use Jackson 3 annotation package
+        Path petModelPath = Paths.get(outputPath + "/src/main/kotlin/org/openapitools/model/Pet.kt");
+        assertFileContains(petModelPath, "tools.jackson.annotation.JsonProperty");
+        assertFileNotContains(petModelPath, "com.fasterxml.jackson.annotation");
+
+        // Enum model with @JsonValue/@JsonCreator must also use Jackson 3
+        Path orderModelPath = Paths.get(outputPath + "/src/main/kotlin/org/openapitools/model/Order.kt");
+        assertFileContains(orderModelPath, "tools.jackson.annotation.JsonValue");
+        assertFileContains(orderModelPath, "tools.jackson.annotation.JsonCreator");
+        assertFileNotContains(orderModelPath, "com.fasterxml.jackson.annotation");
+    }
+
     @Test
     public void shouldDefaultToJackson3WhenSpringBoot4Enabled() throws IOException {
         File output = Files.createTempDirectory("test").toFile().getCanonicalFile();

samples/server/petstore/kotlin-springboot-4/src/main/kotlin/org/openapitools/model/Category.kt

@@ -1,7 +1,7 @@
 package org.openapitools.model
 
 import java.util.Objects
-import com.fasterxml.jackson.annotation.JsonProperty
+import tools.jackson.annotation.JsonProperty
 import jakarta.validation.constraints.DecimalMax
 import jakarta.validation.constraints.DecimalMin
 import jakarta.validation.constraints.Email

samples/server/petstore/kotlin-springboot-4/src/main/kotlin/org/openapitools/model/ModelApiResponse.kt

@@ -1,7 +1,7 @@
 package org.openapitools.model
 
 import java.util.Objects
-import com.fasterxml.jackson.annotation.JsonProperty
+import tools.jackson.annotation.JsonProperty
 import jakarta.validation.constraints.DecimalMax
 import jakarta.validation.constraints.DecimalMin
 import jakarta.validation.constraints.Email

samples/server/petstore/kotlin-springboot-4/src/main/kotlin/org/openapitools/model/Order.kt

@@ -1,9 +1,9 @@
 package org.openapitools.model
 
 import java.util.Objects
-import com.fasterxml.jackson.annotation.JsonCreator
-import com.fasterxml.jackson.annotation.JsonProperty
-import com.fasterxml.jackson.annotation.JsonValue
+import tools.jackson.annotation.JsonCreator
+import tools.jackson.annotation.JsonProperty
+import tools.jackson.annotation.JsonValue
 import jakarta.validation.constraints.DecimalMax
 import jakarta.validation.constraints.DecimalMin
 import jakarta.validation.constraints.Email

samples/server/petstore/kotlin-springboot-4/src/main/kotlin/org/openapitools/model/Pet.kt

@@ -1,11 +1,11 @@
 package org.openapitools.model
 
 import java.util.Objects
-import com.fasterxml.jackson.annotation.JsonCreator
-import com.fasterxml.jackson.annotation.JsonProperty
-import com.fasterxml.jackson.annotation.JsonValue
 import org.openapitools.model.Category
 import org.openapitools.model.Tag
+import tools.jackson.annotation.JsonCreator
+import tools.jackson.annotation.JsonProperty
+import tools.jackson.annotation.JsonValue
 import jakarta.validation.constraints.DecimalMax
 import jakarta.validation.constraints.DecimalMin
 import jakarta.validation.constraints.Email

samples/server/petstore/kotlin-springboot-4/src/main/kotlin/org/openapitools/model/Tag.kt

@@ -1,7 +1,7 @@
 package org.openapitools.model
 
 import java.util.Objects
-import com.fasterxml.jackson.annotation.JsonProperty
+import tools.jackson.annotation.JsonProperty
 import jakarta.validation.constraints.DecimalMax
 import jakarta.validation.constraints.DecimalMin
 import jakarta.validation.constraints.Email

samples/server/petstore/kotlin-springboot-4/src/main/kotlin/org/openapitools/model/User.kt

@@ -1,7 +1,7 @@
 package org.openapitools.model
 
 import java.util.Objects
-import com.fasterxml.jackson.annotation.JsonProperty
+import tools.jackson.annotation.JsonProperty
 import jakarta.validation.constraints.DecimalMax
 import jakarta.validation.constraints.DecimalMin
 import jakarta.validation.constraints.Email