kotlin-server: Fix required + nullable combination for properties (#20054)

* kotlin-server: Fix required + nullable combination

* Update FILES

* Updated generated code

Author: dennisameling

.github/workflows/samples-kotlin-server-jdk17.yaml

@@ -7,6 +7,7 @@ on:
       - 'samples/server/petstore/kotlin-server/**'
       - 'samples/server/petstore/kotlin-server-modelMutable/**'
       - 'samples/server/petstore/kotlin-springboot-*/**'
+      - 'samples/server/petstore/kotlin-server-required-and-nullable-properties/**'
       # comment out due to gradle build failure
       # - samples/server/petstore/kotlin-spring-default/**
   pull_request:
@@ -15,6 +16,7 @@ on:
       - 'samples/server/petstore/kotlin-server/**'
       - 'samples/server/petstore/kotlin-server-modelMutable/**'
       - 'samples/server/petstore/kotlin-springboot-*/**'
+      - 'samples/server/petstore/kotlin-server-required-and-nullable-properties/**'
       # comment out due to gradle build failure
       # - samples/server/petstore/kotlin-spring-default/**
 
@@ -30,6 +32,7 @@ jobs:
       matrix:
         sample:
           # server
+          - samples/server/petstore/kotlin-server-required-and-nullable-properties
           - samples/server/petstore/kotlin-springboot-3
           - samples/server/petstore/kotlin-springboot-delegate-nodefaults
           - samples/server/petstore/kotlin-springboot-request-cookie

.github/workflows/samples-kotlin-server-jdk21.yaml

@@ -4,9 +4,11 @@ on:
   push:
     paths:
       - 'samples/server/petstore/kotlin-server/**'
+      - 'samples/server/petstore/kotlin-server-required-and-nullable-properties/**'
   pull_request:
     paths:
       - 'samples/server/petstore/kotlin-server/**'
+      - 'samples/server/petstore/kotlin-server-required-and-nullable-properties/**'
 
 env:
   GRADLE_VERSION: '8.10'
@@ -21,6 +23,7 @@ jobs:
         sample:
           - samples/server/petstore/kotlin-server/javalin-6
           - samples/server/petstore/kotlin-server/ktor
+          - samples/server/petstore/kotlin-server-required-and-nullable-properties
     steps:
       - uses: actions/checkout@v4
       - uses: actions/setup-java@v4

bin/configs/kotlin-server-required-nullable.yaml

@@ -0,0 +1,7 @@
+generatorName: kotlin-server
+outputDir: samples/server/petstore/kotlin-server-required-and-nullable-properties
+library: javalin6
+inputSpec: modules/openapi-generator/src/test/resources/3_0/required-and-nullable-properties.yaml
+templateDir: modules/openapi-generator/src/main/resources/kotlin-server
+additionalProperties:
+  hideGenerationTimestamp: "true"

modules/openapi-generator/src/main/resources/kotlin-server/data_class_req_var.mustache

@@ -1,4 +1,5 @@
 {{#description}}
     /* {{{.}}} */
 {{/description}}
-    {{>modelMutable}} {{{name}}}: {{#isEnum}}{{{classname}}}.{{{nameInPascalCase}}}{{/isEnum}}{{^isEnum}}{{{dataType}}}{{/isEnum}}
+    {{! Note that required properties may be nullable according to the OpenAPI specification. }}
+    {{>modelMutable}} {{{name}}}: {{#isEnum}}{{{classname}}}.{{{nameInPascalCase}}}{{/isEnum}}{{^isEnum}}{{{dataType}}}{{/isEnum}}{{#isNullable}}?{{/isNullable}}{{#defaultValue}} = {{^isNumber}}{{{defaultValue}}}{{/isNumber}}{{#isNumber}}{{{dataType}}}("{{{defaultValue}}}"){{/isNumber}}{{/defaultValue}}

modules/openapi-generator/src/test/resources/3_0/required-and-nullable-properties.yaml

@@ -0,0 +1,51 @@
+# OpenAPI schemas support 4 possible combinations for properties:
+# 1. nullable + required
+# 2. nullable + not required
+# 3. not nullable + required
+# 4. not nullable + not required
+# This sample contains all of them to demonstrate how they are rendered in the generated code.
+# Related discussion: https://github.com/OpenAPITools/openapi-generator/issues/14765
+openapi: 3.0.3
+info:
+  title: Nullable Required
+  version: 1.0.0
+servers:
+  - url: /api/v3
+paths:
+  /pet:
+    post:
+      operationId: addPet
+      requestBody:
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/Pet'
+      responses:
+        "200":
+          description: Successful operation
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/Pet'
+components:
+  schemas:
+    Pet:
+      required:
+        - notNullable_required
+        - nullable_required
+      type: object
+      properties:
+        nullable_notRequired:
+          type: string
+          example: doggie
+          nullable: true
+        notNullable_notRequired:
+          type: string
+          example: doggie
+        notNullable_required:
+          type: string
+          example: doggie
+        nullable_required:
+          type: string
+          example: doggie
+          nullable: true

samples/server/petstore/kotlin-server-required-and-nullable-properties/.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/server/petstore/kotlin-server-required-and-nullable-properties/.openapi-generator/FILES

@@ -0,0 +1,9 @@
+README.md
+build.gradle.kts
+gradle.properties
+settings.gradle
+src/main/kotlin/org/openapitools/server/Main.kt
+src/main/kotlin/org/openapitools/server/apis/DefaultApi.kt
+src/main/kotlin/org/openapitools/server/apis/DefaultApiService.kt
+src/main/kotlin/org/openapitools/server/apis/DefaultApiServiceImpl.kt
+src/main/kotlin/org/openapitools/server/models/Pet.kt

samples/server/petstore/kotlin-server-required-and-nullable-properties/.openapi-generator/VERSION

@@ -0,0 +1 @@
+7.10.0-SNAPSHOT

samples/server/petstore/kotlin-server-required-and-nullable-properties/README.md

@@ -0,0 +1,60 @@
+# org.openapitools.server - Kotlin Server library for Nullable Required
+
+No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+
+Generated by OpenAPI Generator 7.10.0-SNAPSHOT.
+
+## Build
+
+First, create the gradle wrapper script:
+
+```
+gradle wrapper
+```
+
+Then, run:
+
+```
+./gradlew check assemble
+```
+
+This runs all tests and packages the library.
+
+## Running
+
+The server builds as a fat jar with a main entrypoint. To start the service, run `java -jar ./build/libs/kotlin-server.jar`.
+
+You may also run in docker:
+
+```
+docker build -t kotlin-server .
+docker run -p 8080:8080 kotlin-server
+```
+
+## Features/Implementation Notes
+
+* Supports JSON inputs/outputs, File inputs, and Form inputs (see ktor documentation for more info).
+* ~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 */api/v3*
+
+Class | Method | HTTP request | Description
+------------ | ------------- | ------------- | -------------
+*DefaultApi* | [**addPet**](docs/DefaultApi.md#addpet) | **POST** /pet | 
+
+
+<a id="documentation-for-models"></a>
+## Documentation for Models
+
+ - [org.openapitools.server.models.Pet](docs/Pet.md)
+
+
+<a id="documentation-for-authorization"></a>
+## Documentation for Authorization
+
+Endpoints do not require authorization.
+

samples/server/petstore/kotlin-server-required-and-nullable-properties/build.gradle.kts

@@ -0,0 +1,33 @@
+plugins {
+    kotlin("jvm") version "2.0.21"
+}
+
+group = "org.openapitools"
+version = "1.0.0"
+
+kotlin {
+    jvmToolchain(21)
+}
+
+java {
+    toolchain {
+        languageVersion.set(JavaLanguageVersion.of(21))
+    }
+}
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    implementation("io.javalin:javalin:6.1.6")
+    implementation("com.fasterxml.jackson.core:jackson-databind:2.17.1")
+    implementation("com.fasterxml.jackson.module:jackson-module-kotlin:2.17.1")
+    implementation("org.slf4j:slf4j-simple:2.0.13")
+
+    testImplementation("org.jetbrains.kotlin:kotlin-test")
+}
+
+tasks.test {
+    useJUnitPlatform()
+}