feat(kotlin): Add support for Jackson3 and SpringBoot 4

.github/workflows/samples-kotlin-client.yaml

@@ -31,6 +31,7 @@ jobs:
           - samples/client/petstore/kotlin-explicit
           - samples/client/petstore/kotlin-gson
           - samples/client/petstore/kotlin-jackson
+          - samples/client/petstore/kotlin-jackson3
           - samples/client/petstore/kotlin-model-prefix-type-mappings
           # needs Android configured
           #- samples/client/petstore/kotlin-json-request-string
@@ -74,6 +75,7 @@ jobs:
           - samples/client/petstore/kotlin-jvm-spring-3-restclient
           - samples/client/echo_api/kotlin-jvm-spring-3-restclient
           - samples/client/others/kotlin-jvm-spring-3-restclient-nullable-return
+          - samples/client/petstore/kotlin-jvm-spring-4-restclient-jackson3
           - samples/client/petstore/kotlin-name-parameter-mappings
           - samples/client/others/kotlin-jvm-okhttp-parameter-tests
           - samples/client/others/kotlin-jvm-okhttp-path-comments

bin/configs/kotlin-jackson3.yaml

@@ -0,0 +1,10 @@
+generatorName: kotlin
+outputDir: samples/client/petstore/kotlin-jackson3
+inputSpec: modules/openapi-generator/src/test/resources/2_0/petstore.yaml
+templateDir: modules/openapi-generator/src/main/resources/kotlin-client
+additionalProperties:
+  serializationLibrary: jackson
+  useJackson3: "true"
+  artifactId: kotlin-petstore-jackson3
+  enumPropertyNaming: UPPERCASE
+  enumUnknownDefaultCase: "true"

bin/configs/kotlin-jvm-spring-4-restclient-jackson3.yaml

@@ -0,0 +1,10 @@
+generatorName: kotlin
+outputDir: samples/client/petstore/kotlin-jvm-spring-4-restclient-jackson3
+library: jvm-spring-restclient
+inputSpec: modules/openapi-generator/src/test/resources/3_0/petstore.yaml
+templateDir: modules/openapi-generator/src/main/resources/kotlin-client
+additionalProperties:
+  artifactId: kotlin-petstore-spring4-restclient-jackson3
+  enumUnknownDefaultCase: true
+  serializationLibrary: jackson
+  useSpringBoot4: true

docs/generators/kotlin.md

@@ -32,7 +32,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |groupId|Generated artifact package's organization (i.e. maven groupId).| |org.openapitools|
 |idea|Add IntelliJ Idea plugin and mark Kotlin main and test folders as source folders.| |false|
 |implicitHeaders|Skip header parameters in the generated API methods.| |false|
-|library|Library template (sub-template) to use|<dl><dt>**jvm-ktor**</dt><dd>Platform: Java Virtual Machine. HTTP client: Ktor 1.6.7. JSON processing: Gson, Jackson (default).</dd><dt>**jvm-okhttp4**</dt><dd>[DEFAULT] Platform: Java Virtual Machine. HTTP client: OkHttp 4.2.0 (Android 5.0+ and Java 8+). JSON processing: Moshi 1.8.0.</dd><dt>**jvm-spring-webclient**</dt><dd>Platform: Java Virtual Machine. HTTP: Spring 5 (or 6 with useSpringBoot3 enabled) WebClient. JSON processing: Jackson.</dd><dt>**jvm-spring-restclient**</dt><dd>Platform: Java Virtual Machine. HTTP: Spring 6 RestClient. JSON processing: Jackson.</dd><dt>**jvm-retrofit2**</dt><dd>Platform: Java Virtual Machine. HTTP client: Retrofit 2.6.2.</dd><dt>**multiplatform**</dt><dd>Platform: Kotlin multiplatform. HTTP client: Ktor 1.6.7. JSON processing: Kotlinx Serialization: 1.2.1.</dd><dt>**jvm-volley**</dt><dd>Platform: JVM for Android. HTTP client: Volley 1.2.1. JSON processing: gson 2.8.9 (Deprecated)</dd><dt>**jvm-vertx**</dt><dd>Platform: Java Virtual Machine. HTTP client: Vert.x Web Client. JSON processing: Moshi, Gson or Jackson.</dd></dl>|jvm-okhttp4|
+|library|Library template (sub-template) to use|<dl><dt>**jvm-ktor**</dt><dd>Platform: Java Virtual Machine. HTTP client: Ktor 1.6.7. JSON processing: Gson, Jackson (default).</dd><dt>**jvm-okhttp4**</dt><dd>[DEFAULT] Platform: Java Virtual Machine. HTTP client: OkHttp 4.2.0 (Android 5.0+ and Java 8+). JSON processing: Moshi 1.8.0.</dd><dt>**jvm-spring-webclient**</dt><dd>Platform: Java Virtual Machine. HTTP: Spring 5 (or 6 with useSpringBoot3 enabled) WebClient. JSON processing: Jackson.</dd><dt>**jvm-spring-restclient**</dt><dd>Platform: Java Virtual Machine. HTTP: Spring 6 (or 7 with useSpringBoot4 enabled) RestClient. JSON processing: Jackson.</dd><dt>**jvm-retrofit2**</dt><dd>Platform: Java Virtual Machine. HTTP client: Retrofit 2.6.2.</dd><dt>**multiplatform**</dt><dd>Platform: Kotlin multiplatform. HTTP client: Ktor 1.6.7. JSON processing: Kotlinx Serialization: 1.2.1.</dd><dt>**jvm-volley**</dt><dd>Platform: JVM for Android. HTTP client: Volley 1.2.1. JSON processing: gson 2.8.9 (Deprecated)</dd><dt>**jvm-vertx**</dt><dd>Platform: Java Virtual Machine. HTTP client: Vert.x Web Client. JSON processing: Moshi, Gson or Jackson.</dd></dl>|jvm-okhttp4|
 |mapFileBinaryToByteArray|Map File and Binary to ByteArray (default: false)| |false|
 |modelMutable|Create mutable models| |false|
 |moshiCodeGen|Whether to enable codegen with the Moshi library. Refer to the [official Moshi doc](https://github.com/square/moshi#codegen) for more info.| |false|
@@ -50,12 +50,13 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |sourceFolder|source folder for generated code| |src/main/kotlin|
 |supportAndroidApiLevel25AndBelow|[WARNING] This flag will generate code that has a known security vulnerability. It uses `kotlin.io.createTempFile` instead of `java.nio.file.Files.createTempFile` in order to support Android API level 25 and below. For more info, please check the following links https://github.com/OpenAPITools/openapi-generator/security/advisories/GHSA-23x4-m842-fmwf, https://github.com/OpenAPITools/openapi-generator/pull/9284| |false|
 |useCoroutines|Whether to use the Coroutines adapter with the retrofit2 library.| |false|
-|useJackson3|Use Jackson 3 dependencies (tools.jackson package). Not yet supported for kotlin-client; reserved for future use.| |false|
+|useJackson3|Use Jackson 3 dependencies (tools.jackson package). Requires serializationLibrary=jackson. Incompatible with openApiNullable.| |false|
 |useNonAsciiHeaders|Allow to use non-ascii headers with the okhttp library| |false|
 |useResponseAsReturnType|When using retrofit2 and coroutines, use `Response`&lt;`T`&gt; as return type instead of `T`.| |true|
 |useRxJava3|Whether to use the RxJava3 adapter with the retrofit2 library.| |false|
 |useSettingsGradle|Whether the project uses settings.gradle.| |false|
 |useSpringBoot3|Whether to use the Spring Boot 3 with the jvm-spring-webclient library.| |false|
+|useSpringBoot4|Whether to use the Spring Boot 4 with the jvm-spring-restclient library.| |false|
 
 ## SUPPORTED VENDOR EXTENSIONS
 

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

@@ -92,6 +92,7 @@ public class KotlinClientCodegen extends AbstractKotlinCodegen {
     public static final String USE_SETTINGS_GRADLE = "useSettingsGradle";
     public static final String IDEA = "idea";
     public static final String USE_SPRING_BOOT3 = "useSpringBoot3";
+    public static final String USE_SPRING_BOOT4 = "useSpringBoot4";
     public static final String USE_RESPONSE_AS_RETURN_TYPE = "useResponseAsReturnType";
 
     public static final String DATE_LIBRARY = "dateLibrary";
@@ -252,7 +253,7 @@ public KotlinClientCodegen() {
         supportedLibraries.put(JVM_KTOR, "Platform: Java Virtual Machine. HTTP client: Ktor 1.6.7. JSON processing: Gson, Jackson (default).");
         supportedLibraries.put(JVM_OKHTTP4, "[DEFAULT] Platform: Java Virtual Machine. HTTP client: OkHttp 4.2.0 (Android 5.0+ and Java 8+). JSON processing: Moshi 1.8.0.");
         supportedLibraries.put(JVM_SPRING_WEBCLIENT, "Platform: Java Virtual Machine. HTTP: Spring 5 (or 6 with useSpringBoot3 enabled) WebClient. JSON processing: Jackson.");
-        supportedLibraries.put(JVM_SPRING_RESTCLIENT, "Platform: Java Virtual Machine. HTTP: Spring 6 RestClient. JSON processing: Jackson.");
+        supportedLibraries.put(JVM_SPRING_RESTCLIENT, "Platform: Java Virtual Machine. HTTP: Spring 6 (or 7 with useSpringBoot4 enabled) RestClient. JSON processing: Jackson.");
         supportedLibraries.put(JVM_RETROFIT2, "Platform: Java Virtual Machine. HTTP client: Retrofit 2.6.2.");
         supportedLibraries.put(MULTIPLATFORM, "Platform: Kotlin multiplatform. HTTP client: Ktor 1.6.7. JSON processing: Kotlinx Serialization: 1.2.1.");
         supportedLibraries.put(JVM_VOLLEY, "Platform: JVM for Android. HTTP client: Volley 1.2.1. JSON processing: gson 2.8.9 (Deprecated)");
@@ -275,6 +276,7 @@ public KotlinClientCodegen() {
         cliOptions.add(CliOption.newBoolean(USE_RX_JAVA3, "Whether to use the RxJava3 adapter with the retrofit2 library."));
         cliOptions.add(CliOption.newBoolean(USE_COROUTINES, "Whether to use the Coroutines adapter with the retrofit2 library."));
         cliOptions.add(CliOption.newBoolean(USE_SPRING_BOOT3, "Whether to use the Spring Boot 3 with the jvm-spring-webclient library."));
+        cliOptions.add(CliOption.newBoolean(USE_SPRING_BOOT4, "Whether to use the Spring Boot 4 with the jvm-spring-restclient library."));
         cliOptions.add(CliOption.newBoolean(OMIT_GRADLE_PLUGIN_VERSIONS, "Whether to declare Gradle plugin versions in build files."));
         cliOptions.add(CliOption.newBoolean(OMIT_GRADLE_WRAPPER, "Whether to omit Gradle wrapper for creating a sub project."));
         cliOptions.add(CliOption.newBoolean(USE_SETTINGS_GRADLE, "Whether the project uses settings.gradle."));
@@ -303,8 +305,7 @@ public KotlinClientCodegen() {
         cliOptions.add(CliOption.newBoolean(USE_NON_ASCII_HEADERS, "Allow to use non-ascii headers with the okhttp library"));
         cliOptions.add(CliOption.newBoolean(USE_RESPONSE_AS_RETURN_TYPE, "When using retrofit2 and coroutines, use `Response`<`T`> as return type instead of `T`.", true));
 
-        cliOptions.add(CliOption.newBoolean(USE_JACKSON_3,
-            "Use Jackson 3 dependencies (tools.jackson package). Not yet supported for kotlin-client; reserved for future use."));
+        cliOptions.add(CliOption.newBoolean(USE_JACKSON_3, "Use Jackson 3 dependencies (tools.jackson package). Requires serializationLibrary=jackson. Incompatible with openApiNullable."));
     }
 
     @Override
@@ -473,9 +474,12 @@ public void processOpts() {
             convertPropertyToBooleanAndWriteBack(USE_SPRING_BOOT3);
         }
 
-        if (isUseJackson3()) {
-            throw new IllegalArgumentException(
-                "useJackson3 is not yet supported for kotlin-client. Jackson 3 support for kotlin-client will be added in a future release.");
+        boolean useSpringBoot4 = additionalProperties.containsKey(USE_SPRING_BOOT4)
+                && convertPropertyToBooleanAndWriteBack(USE_SPRING_BOOT4);
+        if (JVM_SPRING_RESTCLIENT.equals(getLibrary()) && useSpringBoot4 && !isUseJackson3()) {
+            setUseJackson3(true);
+            additionalProperties.put(USE_JACKSON_3, true);
+            applyJackson3Package();
         }
 
         if (additionalProperties.containsKey(CodegenConstants.SERIALIZATION_LIBRARY)) {
@@ -485,6 +489,22 @@ public void processOpts() {
             additionalProperties.put(this.serializationLibrary.name(), true);
         }
 
+        if (isUseJackson3()) {
+            if (this.serializationLibrary != SERIALIZATION_LIBRARY_TYPE.jackson) {
+                throw new IllegalArgumentException("useJackson3 requires serializationLibrary=jackson");
+            }
+            if (additionalProperties.containsKey("openApiNullable")
+                    && Boolean.parseBoolean(additionalProperties.get("openApiNullable").toString())) {
+                throw new IllegalArgumentException("openApiNullable cannot be set with useJackson3");
+            }
+            if (!JVM_OKHTTP4.equals(getLibrary()) && !JVM_SPRING_RESTCLIENT.equals(getLibrary())) {
+                throw new IllegalArgumentException("useJackson3 is only supported for the jvm-okhttp4 and jvm-spring-restclient libraries at this time.");
+            }
+            if (JVM_SPRING_RESTCLIENT.equals(getLibrary()) && !useSpringBoot4) {
+                throw new IllegalArgumentException("useJackson3 with jvm-spring-restclient requires useSpringBoot4=true.");
+            }
+        }
+
         if (additionalProperties.containsKey(MAP_FILE_BINARY_TO_BYTE_ARRAY)) {
             setMapFileBinaryToByteArray(convertPropertyToBooleanAndWriteBack(MAP_FILE_BINARY_TO_BYTE_ARRAY));
         }
@@ -868,8 +888,9 @@ private void processJvmSpringWebClientLibrary(final String infrastructureFolder)
     }
 
     private void processJvmSpringRestClientLibrary(final String infrastructureFolder) {
-        if (additionalProperties.getOrDefault(USE_SPRING_BOOT3, false).equals(false)) {
-            throw new RuntimeException("This library must use Spring Boot 3. Try adding '--additional-properties useSpringBoot3=true' to your command.");
+        if (additionalProperties.getOrDefault(USE_SPRING_BOOT3, false).equals(false)
+                && additionalProperties.getOrDefault(USE_SPRING_BOOT4, false).equals(false)) {
+            throw new RuntimeException("This library requires Spring Boot 3 or 4. Try adding '--additional-properties useSpringBoot3=true' or '--additional-properties useSpringBoot4=true' to your command.");
         }
 
         processJvmSpring(infrastructureFolder);

modules/openapi-generator/src/main/resources/kotlin-client/build.gradle.mustache

@@ -23,13 +23,21 @@ buildscript {
     ext.vertx_version = "5.1.5"
     {{/jvm-vertx}}
     {{#jvm-spring}}
+    {{#useSpringBoot4}}
+    ext.spring_boot_version = "4.1.0"
+    {{/useSpringBoot4}}
+    {{^useSpringBoot4}}
     {{#useSpringBoot3}}
     ext.spring_boot_version = "3.5.16"
     {{/useSpringBoot3}}
     {{^useSpringBoot3}}
     ext.spring_boot_version = "2.7.18"
     {{/useSpringBoot3}}
+    {{/useSpringBoot4}}
     {{/jvm-spring}}
+    {{#useJackson3}}
+    ext.jackson3_version = "3.1.5"
+    {{/useJackson3}}
     ext.spotless_version = "7.2.1"
 
     repositories {
@@ -151,8 +159,13 @@ dependencies {
     {{/gson}}
     {{#jackson}}
     implementation "org.jetbrains.kotlin:kotlin-reflect:$kotlin_version"
+    {{#useJackson3}}
+    implementation "tools.jackson.module:jackson-module-kotlin:$jackson3_version"
+    {{/useJackson3}}
+    {{^useJackson3}}
     implementation "com.fasterxml.jackson.module:jackson-module-kotlin:2.22.1"
     implementation "com.fasterxml.jackson.datatype:jackson-datatype-jsr310:2.22.1"
+    {{/useJackson3}}
     {{/jackson}}
     {{#kotlinx_serialization}}
     implementation "org.jetbrains.kotlinx:kotlinx-serialization-json:1.11.0"

modules/openapi-generator/src/main/resources/kotlin-client/jvm-common/infrastructure/Serializer.kt.mustache

@@ -30,11 +30,24 @@ import kotlinx.datetime.LocalTime
 import java.util.UUID
 {{/gson}}
 {{#jackson}}
+{{^useJackson3}}
 import com.fasterxml.jackson.databind.DeserializationFeature
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.fasterxml.jackson.databind.SerializationFeature
 import com.fasterxml.jackson.annotation.JsonInclude
 import com.fasterxml.jackson.module.kotlin.jacksonObjectMapper
+{{/useJackson3}}
+{{#useJackson3}}
+import {{jacksonPackage}}.databind.DeserializationFeature
+import {{jacksonPackage}}.databind.json.JsonMapper
+import {{jacksonPackage}}.databind.cfg.DateTimeFeature
+{{#enumUnknownDefaultCase}}
+import {{jacksonPackage}}.databind.cfg.EnumFeature
+{{/enumUnknownDefaultCase}}
+import com.fasterxml.jackson.annotation.JsonInclude
+import {{jacksonPackage}}.module.kotlin.jsonMapper
+import {{jacksonPackage}}.module.kotlin.kotlinModule
+{{/useJackson3}}
 {{/jackson}}
 {{#kotlinx_serialization}}
 import java.math.BigDecimal
@@ -120,6 +133,7 @@ import java.util.concurrent.atomic.AtomicLong
     }
 {{/gson}}
 {{#jackson}}
+{{^useJackson3}}
     @JvmStatic
     val jacksonObjectMapper: ObjectMapper = jacksonObjectMapper()
         .findAndRegisterModules()
@@ -129,6 +143,24 @@ import java.util.concurrent.atomic.AtomicLong
         {{/enumUnknownDefaultCase}}
         .configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false)
         .configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, {{failOnUnknownProperties}})
+{{/useJackson3}}
+{{#useJackson3}}
+    @JvmStatic
+    val jacksonObjectMapper: JsonMapper = jsonMapper {
+        addModule(kotlinModule())
+        changeDefaultPropertyInclusion { it.withValueInclusion(JsonInclude.Include.NON_ABSENT) }
+        {{#enumUnknownDefaultCase}}
+        enable(EnumFeature.READ_UNKNOWN_ENUM_VALUES_USING_DEFAULT_VALUE)
+        {{/enumUnknownDefaultCase}}
+        disable(DateTimeFeature.WRITE_DATES_AS_TIMESTAMPS)
+        {{#failOnUnknownProperties}}
+        enable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)
+        {{/failOnUnknownProperties}}
+        {{^failOnUnknownProperties}}
+        disable(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES)
+        {{/failOnUnknownProperties}}
+    }
+{{/useJackson3}}
 {{/jackson}}
 {{#kotlinx_serialization}}
     private var isAdaptersInitialized = false

modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-okhttp/infrastructure/ApiClient.kt.mustache

@@ -53,7 +53,7 @@ import org.threeten.bp.OffsetTime
 import com.google.gson.reflect.TypeToken
 {{/gson}}
 {{#jackson}}
-import com.fasterxml.jackson.core.type.TypeReference
+import {{jacksonPackage}}.core.type.TypeReference
 {{/jackson}}
 {{#moshi}}
 import com.squareup.moshi.adapter

modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-spring-restclient/api.mustache

@@ -9,7 +9,13 @@ import org.springframework.web.client.RestClient
 import org.springframework.web.client.RestClientResponseException
 
 {{#jackson}}
+{{^useJackson3}}
 import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter
+{{/useJackson3}}
+{{#useJackson3}}
+import org.springframework.http.converter.json.JacksonJsonHttpMessageConverter
+import {{packageName}}.infrastructure.Serializer
+{{/useJackson3}}
 {{/jackson}}
 import org.springframework.http.ResponseEntity
 import org.springframework.http.MediaType
@@ -23,11 +29,20 @@ import {{packageName}}.infrastructure.*
 {{#nonPublicApi}}internal {{/nonPublicApi}}{{^nonPublicApi}}{{#explicitApi}}public {{/explicitApi}}open {{/nonPublicApi}}class {{classname}}(client: RestClient) : ApiClient(client) {
 
     {{#jackson}}
+    {{^useJackson3}}
     {{^nonPublicApi}}{{#explicitApi}}public {{/explicitApi}}{{/nonPublicApi}}constructor(baseUrl: String) : this(RestClient.builder()
         .baseUrl(baseUrl)
         .messageConverters { it.add(MappingJackson2HttpMessageConverter()) }
         .build()
     )
+    {{/useJackson3}}
+    {{#useJackson3}}
+    {{^nonPublicApi}}{{#explicitApi}}public {{/explicitApi}}{{/nonPublicApi}}constructor(baseUrl: String) : this(RestClient.builder()
+        .baseUrl(baseUrl)
+        .configureMessageConverters { it.registerDefaults().withJsonConverter(JacksonJsonHttpMessageConverter(Serializer.jacksonObjectMapper)) }
+        .build()
+    )
+    {{/useJackson3}}
     {{/jackson}}
 
     {{#operation}}