[BUG](Kotlin): fix double serializable annotation

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

@@ -71,6 +71,7 @@ jobs:
           - samples/client/others/kotlin-jvm-okhttp-path-comments
           - samples/client/others/kotlin-integer-enum
           - samples/client/petstore/kotlin-allOff-discriminator-kotlinx-serialization
+          - samples/client/petstore/kotlin-fix-double-serializable-annotation
     steps:
       - uses: actions/checkout@v5
       - uses: actions/setup-java@v5

bin/configs/kotlin-fix-double-serializable-annotation.yaml

@@ -0,0 +1,10 @@
+generatorName: kotlin
+library: multiplatform
+outputDir: samples/client/petstore/kotlin-fix-double-serializable-annotation
+inputSpec: modules/openapi-generator/src/test/resources/bugs/issue_18904.yaml
+templateDir: modules/openapi-generator/src/main/resources/kotlin-client
+additionalProperties:
+  serializationLibrary: kotlinx_serialization
+  dateLibrary: kotlinx-datetime
+  generateOneOfAnyOfWrappers: true
+

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

@@ -66,7 +66,7 @@ import java.io.IOException
 {{#parcelizeModels}}
 @Parcelize
 {{/parcelizeModels}}
-{{#multiplatform}}{{^discriminator}}@Serializable{{/discriminator}}{{/multiplatform}}{{#kotlinx_serialization}}{{#serializableModel}}@KSerializable{{/serializableModel}}{{^serializableModel}}@Serializable{{/serializableModel}}{{/kotlinx_serialization}}{{#moshi}}{{#moshiCodeGen}}@JsonClass(generateAdapter = true){{/moshiCodeGen}}{{/moshi}}{{#jackson}}{{#discriminator}}{{>typeInfoAnnotation}}{{/discriminator}}{{/jackson}}
+{{#multiplatform}}{{^discriminator}}@Serializable{{/discriminator}}{{/multiplatform}}{{#kotlinx_serialization}}{{#serializableModel}}@KSerializable{{/serializableModel}}{{^serializableModel}}{{^multiplatform}}@Serializable{{/multiplatform}}{{/serializableModel}}{{/kotlinx_serialization}}{{#moshi}}{{#moshiCodeGen}}@JsonClass(generateAdapter = true){{/moshiCodeGen}}{{/moshi}}{{#jackson}}{{#discriminator}}{{>typeInfoAnnotation}}{{/discriminator}}{{/jackson}}
 {{#isDeprecated}}
 @Deprecated(message = "This schema is deprecated.")
 {{/isDeprecated}}

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

@@ -77,7 +77,7 @@ import {{packageName}}.infrastructure.ITransformForStorage
 {{#parcelizeModels}}
 @Parcelize
 {{/parcelizeModels}}
-{{#multiplatform}}@Serializable{{/multiplatform}}{{#kotlinx_serialization}}{{#serializableModel}}@KSerializable{{/serializableModel}}{{^serializableModel}}@Serializable{{/serializableModel}}{{/kotlinx_serialization}}{{#moshi}}{{#moshiCodeGen}}@JsonClass(generateAdapter = true){{/moshiCodeGen}}{{/moshi}}{{#jackson}}{{#discriminator}}{{>typeInfoAnnotation}}{{/discriminator}}{{/jackson}}
+{{#multiplatform}}@Serializable{{/multiplatform}}{{#kotlinx_serialization}}{{#serializableModel}}@KSerializable{{/serializableModel}}{{^serializableModel}}{{^multiplatform}}@Serializable{{/multiplatform}}{{/serializableModel}}{{/kotlinx_serialization}}{{#moshi}}{{#moshiCodeGen}}@JsonClass(generateAdapter = true){{/moshiCodeGen}}{{/moshi}}{{#jackson}}{{#discriminator}}{{>typeInfoAnnotation}}{{/discriminator}}{{/jackson}}
 {{#isDeprecated}}
 @Deprecated(message = "This schema is deprecated.")
 {{/isDeprecated}}

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

@@ -46,7 +46,7 @@ import kotlinx.serialization.*
  *
  * Values: {{#allowableValues}}{{#enumVars}}{{&name}}{{^-last}},{{/-last}}{{/enumVars}}{{/allowableValues}}
  */
-{{#multiplatform}}@Serializable{{/multiplatform}}{{#kotlinx_serialization}}@Serializable{{#enumUnknownDefaultCase}}(with = {{classname}}Serializer::class){{/enumUnknownDefaultCase}}{{^enumUnknownDefaultCase}}{{^isString}}(with = {{classname}}Serializer::class){{/isString}}{{/enumUnknownDefaultCase}}{{/kotlinx_serialization}}
+{{#multiplatform}}@Serializable{{/multiplatform}}{{#kotlinx_serialization}}{{^multiplatform}}@Serializable{{/multiplatform}}{{#enumUnknownDefaultCase}}(with = {{classname}}Serializer::class){{/enumUnknownDefaultCase}}{{^enumUnknownDefaultCase}}{{^isString}}(with = {{classname}}Serializer::class){{/isString}}{{/enumUnknownDefaultCase}}{{/kotlinx_serialization}}
 {{^multiplatform}}
 {{#moshi}}
 @JsonClass(generateAdapter = false)

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

@@ -66,7 +66,7 @@ import java.io.IOException
 {{#parcelizeModels}}
 @Parcelize
 {{/parcelizeModels}}
-{{#multiplatform}}{{^discriminator}}@Serializable{{/discriminator}}{{/multiplatform}}{{#kotlinx_serialization}}{{#serializableModel}}@KSerializable{{/serializableModel}}{{^serializableModel}}@Serializable{{/serializableModel}}{{/kotlinx_serialization}}{{#moshi}}{{#moshiCodeGen}}@JsonClass(generateAdapter = true){{/moshiCodeGen}}{{/moshi}}{{#jackson}}{{#discriminator}}{{>typeInfoAnnotation}}{{/discriminator}}{{/jackson}}
+{{#multiplatform}}{{^discriminator}}@Serializable{{/discriminator}}{{/multiplatform}}{{#kotlinx_serialization}}{{#serializableModel}}@KSerializable{{/serializableModel}}{{^serializableModel}}{{^multiplatform}}@Serializable{{/multiplatform}}{{/serializableModel}}{{/kotlinx_serialization}}{{#moshi}}{{#moshiCodeGen}}@JsonClass(generateAdapter = true){{/moshiCodeGen}}{{/moshi}}{{#jackson}}{{#discriminator}}{{>typeInfoAnnotation}}{{/discriminator}}{{/jackson}}
 {{#isDeprecated}}
 @Deprecated(message = "This schema is deprecated.")
 {{/isDeprecated}}

modules/openapi-generator/src/test/resources/bugs/issue_18904.yaml

@@ -0,0 +1,64 @@
+openapi: 3.0.3
+info: { title: demo, version: 1.0.0 }
+paths: {}
+components:
+  schemas:
+
+    # data_class + enum_class
+    Pet:
+      type: object
+      required: [id, name, kind]
+      properties:
+        id:   { type: string }
+        name: { type: string }
+        kind: { $ref: '#/components/schemas/PetKind' }
+
+    PetKind:
+      type: string
+      enum: [cat, dog, fish]
+
+    # oneOf no discriminator
+    Animal:
+      oneOf:
+        - $ref: '#/components/schemas/Cat'
+        - $ref: '#/components/schemas/Dog'
+
+    Cat:
+      type: object
+      required: [kind, meow]
+      properties:
+        kind:
+          type: string
+          enum: [cat]
+        meow:
+          type: string
+
+    Dog:
+      type: object
+      required: [kind, bark]
+      properties:
+        kind:
+          type: string
+          enum: [dog]
+        bark:
+          type: string
+
+    # anyOf no discriminator
+    Device:
+      anyOf:
+        - $ref: '#/components/schemas/Phone'
+        - $ref: '#/components/schemas/Laptop'
+
+    Phone:
+      type: object
+      required: [model, number]
+      properties:
+        model:  { type: string }
+        number: { type: string }
+
+    Laptop:
+      type: object
+      required: [model, ramGb]
+      properties:
+        model: { type: string }
+        ramGb: { type: integer, format: int32 }

samples/client/petstore/kotlin-fix-double-serializable-annotation/.openapi-generator-ignore

@@ -0,0 +1,23 @@
+# OpenAPI Generator Ignore
+# Generated by openapi-generator https://github.com/openapitools/openapi-generator
+
+# Use this file to prevent files from being overwritten by the generator.
+# The patterns follow closely to .gitignore or .dockerignore.
+
+# As an example, the C# client generator defines ApiClient.cs.
+# You can make changes and tell OpenAPI Generator to ignore just this file by uncommenting the following line:
+#ApiClient.cs
+
+# You can match any string of characters against a directory, file or extension with a single asterisk (*):
+#foo/*/qux
+# The above matches foo/bar/qux and foo/baz/qux, but not foo/bar/baz/qux
+
+# You can recursively match patterns against a directory, file or extension with a double asterisk (**):
+#foo/**/qux
+# This matches foo/bar/qux, foo/baz/qux, and foo/bar/baz/qux
+
+# You can also negate patterns with an exclamation (!).
+# For example, you can ignore all files in a docs folder with the file extension .md:
+#docs/*.md
+# Then explicitly reverse the ignore rule for a single file:
+#!docs/README.md

samples/client/petstore/kotlin-fix-double-serializable-annotation/.openapi-generator/FILES

@@ -0,0 +1,46 @@
+.openapi-generator-ignore
+README.md
+build.gradle.kts
+docs/Animal.md
+docs/Cat.md
+docs/Device.md
+docs/Dog.md
+docs/Laptop.md
+docs/Pet.md
+docs/PetKind.md
+docs/Phone.md
+gradle/wrapper/gradle-wrapper.jar
+gradle/wrapper/gradle-wrapper.properties
+gradlew
+gradlew.bat
+settings.gradle.kts
+src/commonMain/kotlin/org/openapitools/client/auth/ApiKeyAuth.kt
+src/commonMain/kotlin/org/openapitools/client/auth/Authentication.kt
+src/commonMain/kotlin/org/openapitools/client/auth/HttpBasicAuth.kt
+src/commonMain/kotlin/org/openapitools/client/auth/HttpBearerAuth.kt
+src/commonMain/kotlin/org/openapitools/client/auth/OAuth.kt
+src/commonMain/kotlin/org/openapitools/client/infrastructure/ApiAbstractions.kt
+src/commonMain/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
+src/commonMain/kotlin/org/openapitools/client/infrastructure/Base64ByteArray.kt
+src/commonMain/kotlin/org/openapitools/client/infrastructure/Bytes.kt
+src/commonMain/kotlin/org/openapitools/client/infrastructure/HttpResponse.kt
+src/commonMain/kotlin/org/openapitools/client/infrastructure/OctetByteArray.kt
+src/commonMain/kotlin/org/openapitools/client/infrastructure/PartConfig.kt
+src/commonMain/kotlin/org/openapitools/client/infrastructure/RequestConfig.kt
+src/commonMain/kotlin/org/openapitools/client/infrastructure/RequestMethod.kt
+src/commonMain/kotlin/org/openapitools/client/models/Animal.kt
+src/commonMain/kotlin/org/openapitools/client/models/Cat.kt
+src/commonMain/kotlin/org/openapitools/client/models/Device.kt
+src/commonMain/kotlin/org/openapitools/client/models/Dog.kt
+src/commonMain/kotlin/org/openapitools/client/models/Laptop.kt
+src/commonMain/kotlin/org/openapitools/client/models/Pet.kt
+src/commonMain/kotlin/org/openapitools/client/models/PetKind.kt
+src/commonMain/kotlin/org/openapitools/client/models/Phone.kt
+src/test/kotlin/org/openapitools/client/models/AnimalTest.kt
+src/test/kotlin/org/openapitools/client/models/CatTest.kt
+src/test/kotlin/org/openapitools/client/models/DeviceTest.kt
+src/test/kotlin/org/openapitools/client/models/DogTest.kt
+src/test/kotlin/org/openapitools/client/models/LaptopTest.kt
+src/test/kotlin/org/openapitools/client/models/PetKindTest.kt
+src/test/kotlin/org/openapitools/client/models/PetTest.kt
+src/test/kotlin/org/openapitools/client/models/PhoneTest.kt

samples/client/petstore/kotlin-fix-double-serializable-annotation/.openapi-generator/VERSION

@@ -0,0 +1 @@
+7.16.0-SNAPSHOT

samples/client/petstore/kotlin-fix-double-serializable-annotation/README.md

@@ -0,0 +1,58 @@
+# org.openapitools.client - Kotlin client library for demo
+
+No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+
+## Overview
+This API client was generated by the [OpenAPI Generator](https://openapi-generator.tech) project.  By using the [openapi-spec](https://github.com/OAI/OpenAPI-Specification) from a remote server, you can easily generate an API client.
+
+- API version: 1.0.0
+- Package version: 
+- Generator version: 7.16.0-SNAPSHOT
+- Build package: org.openapitools.codegen.languages.KotlinClientCodegen
+
+## Requires
+
+* Kotlin 1.5.10
+
+## Build
+
+```
+./gradlew check assemble
+```
+
+This runs all tests and packages the library.
+
+## Features/Implementation Notes
+
+* Supports JSON inputs/outputs, File inputs, and Form inputs.
+* Supports collection formats for query parameters: csv, tsv, ssv, pipes.
+* Some Kotlin and Java types are fully qualified to avoid conflicts with types defined in OpenAPI definitions.
+
+
+<a id="documentation-for-api-endpoints"></a>
+## Documentation for API Endpoints
+
+All URIs are relative to *http://localhost*
+
+| Class | Method | HTTP request | Description |
+| ------------ | ------------- | ------------- | ------------- |
+
+
+<a id="documentation-for-models"></a>
+## Documentation for Models
+
+ - [org.openapitools.client.models.Animal](docs/Animal.md)
+ - [org.openapitools.client.models.Cat](docs/Cat.md)
+ - [org.openapitools.client.models.Device](docs/Device.md)
+ - [org.openapitools.client.models.Dog](docs/Dog.md)
+ - [org.openapitools.client.models.Laptop](docs/Laptop.md)
+ - [org.openapitools.client.models.Pet](docs/Pet.md)
+ - [org.openapitools.client.models.PetKind](docs/PetKind.md)
+ - [org.openapitools.client.models.Phone](docs/Phone.md)
+
+
+<a id="documentation-for-authorization"></a>
+## Documentation for Authorization
+
+Endpoints do not require authorization.
+

samples/client/petstore/kotlin-fix-double-serializable-annotation/build.gradle.kts

@@ -0,0 +1,95 @@
+import org.jetbrains.kotlin.gradle.plugin.mpp.KotlinNativeTarget
+
+plugins {
+    kotlin("multiplatform") version "2.1.21" // kotlin_version
+    kotlin("plugin.serialization") version "2.1.21" // kotlin_version
+}
+
+group = "org.openapitools"
+version = "1.0.0"
+
+val kotlin_version = "2.1.21"
+val coroutines_version = "1.10.2"
+val serialization_version = "1.8.1"
+val ktor_version = "3.1.3"
+
+repositories {
+    mavenCentral()
+}
+
+kotlin {
+    jvm()
+    iosX64()
+    iosArm64()
+    iosSimulatorArm64()
+    js {
+        browser()
+        nodejs()
+    }
+
+    sourceSets {
+        commonMain {
+            dependencies {
+                implementation("org.jetbrains.kotlinx:kotlinx-coroutines-core:$coroutines_version")
+                implementation("org.jetbrains.kotlinx:kotlinx-serialization-core:$serialization_version")
+
+                api("io.ktor:ktor-client-core:$ktor_version")
+                api("io.ktor:ktor-client-serialization:$ktor_version")
+                api("io.ktor:ktor-client-content-negotiation:$ktor_version")
+                api("io.ktor:ktor-serialization-kotlinx-json:$ktor_version")
+
+                api("org.jetbrains.kotlinx:kotlinx-datetime:0.6.2")
+            }
+        }
+
+        commonTest {
+            dependencies {
+                implementation(kotlin("test"))
+                implementation("io.ktor:ktor-client-mock:$ktor_version")
+            }
+        }
+
+        jvmMain {
+            dependencies {
+                implementation(kotlin("stdlib-jdk7"))
+                implementation("io.ktor:ktor-client-cio-jvm:$ktor_version")
+            }
+        }
+
+        jvmTest {
+            dependencies {
+                implementation(kotlin("test-junit"))
+            }
+        }
+
+        iosMain {
+            dependencies {
+                api("io.ktor:ktor-client-ios:$ktor_version")
+            }
+        }
+
+        jsMain {
+            dependencies {
+                api("io.ktor:ktor-client-js:$ktor_version")
+            }
+        }
+    }
+}
+
+tasks {
+    register("iosTest") {
+        val device = project.findProperty("device")?.toString() ?: "iPhone 8"
+        dependsOn("linkDebugTestIosX64")
+        group = JavaBasePlugin.VERIFICATION_GROUP
+        description = "Execute unit tests on ${device} simulator"
+        doLast {
+            val binary = kotlin.targets.getByName<KotlinNativeTarget>("iosX64").binaries.getTest("DEBUG")
+            exec {
+                commandLine("xcrun", "simctl", "spawn", device, binary.outputFile)
+            }
+        }
+    }
+    register("test") {
+        dependsOn("allTests")
+    }
+}

samples/client/petstore/kotlin-fix-double-serializable-annotation/docs/Animal.md

@@ -0,0 +1,19 @@
+
+# Animal
+
+## Properties
+| Name | Type | Description | Notes |
+| ------------ | ------------- | ------------- | ------------- |
+| **kind** | [**inline**](#Kind) |  |  |
+| **meow** | **kotlin.String** |  |  |
+| **bark** | **kotlin.String** |  |  |
+
+
+<a id="Kind"></a>
+## Enum: kind
+| Name | Value |
+| ---- | ----- |
+| kind | dog |
+
+
+

samples/client/petstore/kotlin-fix-double-serializable-annotation/docs/Cat.md

@@ -0,0 +1,18 @@
+
+# Cat
+
+## Properties
+| Name | Type | Description | Notes |
+| ------------ | ------------- | ------------- | ------------- |
+| **kind** | [**inline**](#Kind) |  |  |
+| **meow** | **kotlin.String** |  |  |
+
+
+<a id="Kind"></a>
+## Enum: kind
+| Name | Value |
+| ---- | ----- |
+| kind | cat |
+
+
+

samples/client/petstore/kotlin-fix-double-serializable-annotation/docs/Device.md

@@ -0,0 +1,12 @@
+
+# Device
+
+## Properties
+| Name | Type | Description | Notes |
+| ------------ | ------------- | ------------- | ------------- |
+| **model** | **kotlin.String** |  |  |
+| **number** | **kotlin.String** |  |  |
+| **ramGb** | **kotlin.Int** |  |  |
+
+
+