[kotlin-server] Add polymorphism, oneOf and allOf support (#22610)

* [kotlin-server] Add polymorphism support

* Fix CI triggers

* Fix FILES

* Fix samples and related triggers

* Fix FILES

* Add discriminator property to sealed class

* Fix double nullability issue

* Update samples

Author: Dennis Ameling

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

@@ -3,6 +3,7 @@ name: Samples Kotlin server (jdk17)
 on:
   push:
     paths:
+      - 'samples/server/others/kotlin-server/**'
       - 'samples/server/petstore/kotlin-springboot-3*/**'
       - 'samples/server/petstore/kotlin-server/**'
       - 'samples/server/petstore/kotlin-server-modelMutable/**'
@@ -13,6 +14,7 @@ on:
       # - samples/server/petstore/kotlin-spring-default/**
   pull_request:
     paths:
+      - 'samples/server/others/kotlin-server/**'
       - 'samples/server/petstore/kotlin-springboot-3*/**'
       - 'samples/server/petstore/kotlin-server/**'
       - 'samples/server/petstore/kotlin-server-modelMutable/**'
@@ -34,6 +36,10 @@ jobs:
       matrix:
         sample:
           # server
+          - samples/server/others/kotlin-server/polymorphism-allof-and-discriminator
+          - samples/server/others/kotlin-server/polymorphism-and-discriminator-disabled-jackson-fix
+          - samples/server/others/kotlin-server/polymorphism-and-discriminator
+          - samples/server/others/kotlin-server/polymorphism
           - samples/server/petstore/kotlin-server-required-and-nullable-properties
           - samples/server/petstore/kotlin-springboot-3
           - samples/server/petstore/kotlin-springboot-3-no-response-entity

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

@@ -3,10 +3,12 @@ name: Samples Kotlin server (jdk21)
 on:
   push:
     paths:
+      - 'samples/server/others/kotlin-server/**'
       - 'samples/server/petstore/kotlin-server/**'
       - 'samples/server/petstore/kotlin-server-required-and-nullable-properties/**'
   pull_request:
     paths:
+      - 'samples/server/others/kotlin-server/**'
       - 'samples/server/petstore/kotlin-server/**'
       - 'samples/server/petstore/kotlin-server-required-and-nullable-properties/**'
 
@@ -21,6 +23,10 @@ jobs:
       fail-fast: false
       matrix:
         sample:
+          - samples/server/others/kotlin-server/polymorphism-allof-and-discriminator
+          - samples/server/others/kotlin-server/polymorphism-and-discriminator-disabled-jackson-fix
+          - samples/server/others/kotlin-server/polymorphism-and-discriminator
+          - samples/server/others/kotlin-server/polymorphism
           - samples/server/petstore/kotlin-server/javalin-6
           - samples/server/petstore/kotlin-server/ktor
           - samples/server/petstore/kotlin-server/ktor2

bin/configs/kotlin-server-polymorphism-allof-and-discriminator.yaml

@@ -0,0 +1,7 @@
+generatorName: kotlin-server
+outputDir: samples/server/others/kotlin-server/polymorphism-allof-and-discriminator
+inputSpec: modules/openapi-generator/src/test/resources/3_1/polymorphism-allof-and-discriminator.yaml
+templateDir: modules/openapi-generator/src/main/resources/kotlin-server
+additionalProperties:
+  artifactId: kotlin-server-polymorphism-allof-and-discriminator
+  library: javalin6

bin/configs/kotlin-server-polymorphism-and-discriminator-disabled-jackson-fix.yaml

@@ -0,0 +1,10 @@
+generatorName: kotlin-server
+outputDir: samples/server/others/kotlin-server/polymorphism-and-discriminator-disabled-jackson-fix
+inputSpec: modules/openapi-generator/src/test/resources/3_1/polymorphism-and-discriminator.yaml
+templateDir: modules/openapi-generator/src/main/resources/kotlin-server
+additionalProperties:
+  artifactId: kotlin-server-polymorphism-and-discriminator-disabled-jackson-fix
+  library: javalin6
+  # This is set to "true" by default, but we also want to test the case where it's set to false.
+  # See KotlinServerCodegen.java for more details about this property.
+  fixJacksonJsonTypeInfoInheritance: false

bin/configs/kotlin-server-polymorphism-and-discriminator.yaml

@@ -0,0 +1,8 @@
+generatorName: kotlin-server
+outputDir: samples/server/others/kotlin-server/polymorphism-and-discriminator
+inputSpec: modules/openapi-generator/src/test/resources/3_1/polymorphism-and-discriminator.yaml
+templateDir: modules/openapi-generator/src/main/resources/kotlin-server
+additionalProperties:
+  artifactId: kotlin-server-polymorphism-and-discriminator
+  library: javalin6
+  fixJacksonJsonTypeInfoInheritance: true

bin/configs/kotlin-server-polymorphism.yaml

@@ -0,0 +1,7 @@
+generatorName: kotlin-server
+outputDir: samples/server/others/kotlin-server/polymorphism
+inputSpec: modules/openapi-generator/src/test/resources/3_1/polymorphism.yaml
+templateDir: modules/openapi-generator/src/main/resources/kotlin-server
+additionalProperties:
+  artifactId: kotlin-server-polymorphism
+  library: javalin6

docs/generators/kotlin-server.md

@@ -30,6 +30,7 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 |featureHSTS|Avoid sending content if client already has same content, by checking ETag or LastModified properties.| |true|
 |featureMetrics|Enables metrics feature.| |true|
 |featureResources|Generates routes in a typed way, for both: constructing URLs and reading the parameters.| |true|
+|fixJacksonJsonTypeInfoInheritance|When true (default), ensures Jackson polymorphism works correctly by: (1) always setting visible=true on @JsonTypeInfo, and (2) adding the discriminator property to child models with appropriate default values. When false, visible is only set to true if all children already define the discriminator property.| |true|
 |groupId|Generated artifact package's organization (i.e. maven groupId).| |org.openapitools|
 |interfaceOnly|Whether to generate only API interface stubs without the server files. This option is currently supported only when using jaxrs-spec library.| |false|
 |library|library template (sub-template)|<dl><dt>**ktor**</dt><dd>ktor framework</dd><dt>**ktor2**</dt><dd>ktor (2.x) framework</dd><dt>**jaxrs-spec**</dt><dd>JAX-RS spec only</dd><dt>**javalin5**</dt><dd>Javalin 5</dd><dt>**javalin6**</dt><dd>Javalin 6</dd></dl>|ktor|
@@ -262,11 +263,11 @@ These options may be applied as additional-properties (cli) or configOptions (pl
 | ---- | --------- | ---------- |
 |Simple|✓|OAS2,OAS3
 |Composite|✓|OAS2,OAS3
-|Polymorphism|✗|OAS2,OAS3
+|Polymorphism|✓|OAS2,OAS3
 |Union|✗|OAS3
-|allOf|✗|OAS2,OAS3
+|allOf|✓|OAS2,OAS3
 |anyOf|✗|OAS3
-|oneOf|✗|OAS3
+|oneOf|✓|OAS3
 |not|✗|OAS3
 
 ### Security Feature