diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/KotlinServerCodegen.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/KotlinServerCodegen.java
index 885449a51354..6473308d2164 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/KotlinServerCodegen.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/KotlinServerCodegen.java
@@ -294,7 +294,7 @@ public void processOpts() {
 
         String gradleBuildFile = "build.gradle";
 
-        if (isJavalin() || isKtor()) {
+        if (isJavalin() || isKtor2Or3()) {
             gradleBuildFile = "build.gradle.kts";
         }
 
@@ -302,7 +302,7 @@ public void processOpts() {
         supportingFiles.add(new SupportingFile("settings.gradle.mustache", "", "settings.gradle"));
         supportingFiles.add(new SupportingFile("gradle.properties", "", "gradle.properties"));
 
-        if (isKtor()) {
+        if (isKtor2Or3()) {
             additionalProperties.put(Constants.IS_KTOR, true);
 
             supportingFiles.add(new SupportingFile("AppMain.kt.mustache", packageFolder, "AppMain.kt"));
@@ -445,7 +445,20 @@ private boolean isJavalin() {
         return Constants.JAVALIN5.equals(library) || Constants.JAVALIN6.equals(library);
     }
 
-    private boolean isKtor() {
+    private boolean isKtor2Or3() {
         return Constants.KTOR.equals(library) || Constants.KTOR2.equals(library);
     }
+
+    /**
+     * Returns true if latest version of ktor is used.
+     *
+     * @return true if latest veresion of ktor is used.
+     */
+    private boolean isKtor() {
+        return Constants.KTOR.equals(library);
+    }
+
+    private boolean isKtor2() {
+        return Constants.KTOR2.equals(library);
+    }
 }
diff --git a/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt b/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
index 4b9802b38741..e69de29bb2d1 100644
--- a/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
+++ b/samples/client/petstore/kotlin-moshi-codegen/src/main/kotlin/org/openapitools/client/infrastructure/Serializer.kt
@@ -1,21 +0,0 @@
-package org.openapitools.client.infrastructure
-
-import com.squareup.moshi.Moshi
-
-object Serializer {
-    @JvmStatic
-    val moshiBuilder: Moshi.Builder = Moshi.Builder()
-        .add(OffsetDateTimeAdapter())
-        .add(LocalDateTimeAdapter())
-        .add(LocalDateAdapter())
-        .add(UUIDAdapter())
-        .add(ByteArrayAdapter())
-        .add(URIAdapter())
-        .add(BigDecimalAdapter())
-        .add(BigIntegerAdapter())
-
-    @JvmStatic
-    val moshi: Moshi by lazy {
-        moshiBuilder.build()
-    }
-}
diff --git a/samples/server/petstore/kotlin-server/ktor2/.openapi-generator/FILES b/samples/server/petstore/kotlin-server/ktor2/.openapi-generator/FILES
index 52c6d592e8f2..e574509f97d7 100644
--- a/samples/server/petstore/kotlin-server/ktor2/.openapi-generator/FILES
+++ b/samples/server/petstore/kotlin-server/ktor2/.openapi-generator/FILES
@@ -1,4 +1,3 @@
-Dockerfile
 README.md
 build.gradle.kts
 gradle.properties
diff --git a/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/apis/PetApi.kt b/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/apis/PetApi.kt
index 7b0482f3d322..fdb4e1552d9d 100644
--- a/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/apis/PetApi.kt
+++ b/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/apis/PetApi.kt
@@ -36,7 +36,7 @@ fun Route.PetApi() {
     authenticate("petstore_auth") {
     post<Paths.addPet> {
         
-        val principal = call.authentication.principal<OAuthAccessTokenResponse>()!!
+        val principal = call.authentication.principal<OAuthAccessTokenResponse>()
         
         
         val exampleContentType = "application/json"
@@ -70,7 +70,7 @@ fun Route.PetApi() {
     authenticate("petstore_auth") {
     delete<Paths.deletePet> {
         
-        val principal = call.authentication.principal<OAuthAccessTokenResponse>()!!
+        val principal = call.authentication.principal<OAuthAccessTokenResponse>()
         
         
         call.respond(HttpStatusCode.NotImplemented)
@@ -81,7 +81,7 @@ fun Route.PetApi() {
     authenticate("petstore_auth") {
     get<Paths.findPetsByStatus> {
         
-        val principal = call.authentication.principal<OAuthAccessTokenResponse>()!!
+        val principal = call.authentication.principal<OAuthAccessTokenResponse>()
         
         
         val exampleContentType = "application/json"
@@ -131,7 +131,7 @@ fun Route.PetApi() {
     authenticate("petstore_auth") {
     get<Paths.findPetsByTags> {
         
-        val principal = call.authentication.principal<OAuthAccessTokenResponse>()!!
+        val principal = call.authentication.principal<OAuthAccessTokenResponse>()
         
         
         val exampleContentType = "application/json"
@@ -181,7 +181,7 @@ fun Route.PetApi() {
     authenticate("api_key") {
     get<Paths.getPetById> {
         
-        val principal = call.authentication.principal<ApiPrincipal>()!!
+        val principal = call.authentication.principal<ApiPrincipal>()
         
         
         val exampleContentType = "application/json"
@@ -215,7 +215,7 @@ fun Route.PetApi() {
     authenticate("petstore_auth") {
     put<Paths.updatePet> {
         
-        val principal = call.authentication.principal<OAuthAccessTokenResponse>()!!
+        val principal = call.authentication.principal<OAuthAccessTokenResponse>()
         
         
         val exampleContentType = "application/json"
@@ -249,7 +249,7 @@ fun Route.PetApi() {
     authenticate("petstore_auth") {
     post<Paths.updatePetWithForm> {
         
-        val principal = call.authentication.principal<OAuthAccessTokenResponse>()!!
+        val principal = call.authentication.principal<OAuthAccessTokenResponse>()
         
         
         call.respond(HttpStatusCode.NotImplemented)
@@ -260,7 +260,7 @@ fun Route.PetApi() {
     authenticate("petstore_auth") {
     post<Paths.uploadFile> {
         
-        val principal = call.authentication.principal<OAuthAccessTokenResponse>()!!
+        val principal = call.authentication.principal<OAuthAccessTokenResponse>()
         
         
         val exampleContentType = "application/json"
diff --git a/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/apis/StoreApi.kt b/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/apis/StoreApi.kt
index fe780f7feb46..baaf8adce0f4 100644
--- a/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/apis/StoreApi.kt
+++ b/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/apis/StoreApi.kt
@@ -40,7 +40,7 @@ fun Route.StoreApi() {
     authenticate("api_key") {
     get<Paths.getInventory> {
         
-        val principal = call.authentication.principal<ApiPrincipal>()!!
+        val principal = call.authentication.principal<ApiPrincipal>()
         
         
         call.respond(HttpStatusCode.NotImplemented)
@@ -60,7 +60,7 @@ fun Route.StoreApi() {
         }"""
         
         when (exampleContentType) {
-            "application/json" -> call.respond(gson.fromJson(exampleContentString, empty::class.java))
+            "application/json" -> call.respondText(exampleContentType, ContentType.Application.Json)
             "application/xml" -> call.respondText(exampleContentString, ContentType.Text.Xml)
             else -> call.respondText(exampleContentString)
         }
@@ -79,7 +79,7 @@ fun Route.StoreApi() {
         }"""
         
         when (exampleContentType) {
-            "application/json" -> call.respond(gson.fromJson(exampleContentString, empty::class.java))
+            "application/json" -> call.respondText(exampleContentType, ContentType.Application.Json)
             "application/xml" -> call.respondText(exampleContentString, ContentType.Text.Xml)
             else -> call.respondText(exampleContentString)
         }
diff --git a/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/apis/UserApi.kt b/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/apis/UserApi.kt
index f3b7a76c39a0..7a62e6dab1c5 100644
--- a/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/apis/UserApi.kt
+++ b/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/apis/UserApi.kt
@@ -35,7 +35,7 @@ fun Route.UserApi() {
     authenticate("api_key") {
     post<Paths.createUser> {
         
-        val principal = call.authentication.principal<ApiPrincipal>()!!
+        val principal = call.authentication.principal<ApiPrincipal>()
         
         
         call.respond(HttpStatusCode.NotImplemented)
@@ -46,7 +46,7 @@ fun Route.UserApi() {
     authenticate("api_key") {
     post<Paths.createUsersWithArrayInput> {
         
-        val principal = call.authentication.principal<ApiPrincipal>()!!
+        val principal = call.authentication.principal<ApiPrincipal>()
         
         
         call.respond(HttpStatusCode.NotImplemented)
@@ -57,7 +57,7 @@ fun Route.UserApi() {
     authenticate("api_key") {
     post<Paths.createUsersWithListInput> {
         
-        val principal = call.authentication.principal<ApiPrincipal>()!!
+        val principal = call.authentication.principal<ApiPrincipal>()
         
         
         call.respond(HttpStatusCode.NotImplemented)
@@ -68,7 +68,7 @@ fun Route.UserApi() {
     authenticate("api_key") {
     delete<Paths.deleteUser> {
         
-        val principal = call.authentication.principal<ApiPrincipal>()!!
+        val principal = call.authentication.principal<ApiPrincipal>()
         
         
         call.respond(HttpStatusCode.NotImplemented)
@@ -90,7 +90,7 @@ fun Route.UserApi() {
         }"""
         
         when (exampleContentType) {
-            "application/json" -> call.respond(gson.fromJson(exampleContentString, empty::class.java))
+            "application/json" -> call.respondText(exampleContentType, ContentType.Application.Json)
             "application/xml" -> call.respondText(exampleContentString, ContentType.Text.Xml)
             else -> call.respondText(exampleContentString)
         }
@@ -105,7 +105,7 @@ fun Route.UserApi() {
     authenticate("api_key") {
     get<Paths.logoutUser> {
         
-        val principal = call.authentication.principal<ApiPrincipal>()!!
+        val principal = call.authentication.principal<ApiPrincipal>()
         
         
         call.respond(HttpStatusCode.NotImplemented)
@@ -116,7 +116,7 @@ fun Route.UserApi() {
     authenticate("api_key") {
     put<Paths.updateUser> {
         
-        val principal = call.authentication.principal<ApiPrincipal>()!!
+        val principal = call.authentication.principal<ApiPrincipal>()
         
         
         call.respond(HttpStatusCode.NotImplemented)
diff --git a/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/models/Category.kt b/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/models/Category.kt
index 9d8571921384..7647c2d227e0 100644
--- a/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/models/Category.kt
+++ b/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/models/Category.kt
@@ -12,19 +12,17 @@
 package org.openapitools.server.models
 
 
-import java.io.Serializable
+import kotlinx.serialization.Serializable
 /**
  * A category for a pet
  * @param id 
  * @param name 
  */
+@Serializable
 data class Category(
     val id: kotlin.Long? = null,
     val name: kotlin.String? = null
-) : Serializable 
+)
 {
-    companion object {
-        private const val serialVersionUID: Long = 123
-    }
 }
 
diff --git a/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/models/ModelApiResponse.kt b/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/models/ModelApiResponse.kt
index 5548175d9048..e16d42e86a4e 100644
--- a/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/models/ModelApiResponse.kt
+++ b/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/models/ModelApiResponse.kt
@@ -12,21 +12,19 @@
 package org.openapitools.server.models
 
 
-import java.io.Serializable
+import kotlinx.serialization.Serializable
 /**
  * Describes the result of uploading an image resource
  * @param code 
  * @param type 
  * @param message 
  */
+@Serializable
 data class ModelApiResponse(
     val code: kotlin.Int? = null,
     val type: kotlin.String? = null,
     val message: kotlin.String? = null
-) : Serializable 
+)
 {
-    companion object {
-        private const val serialVersionUID: Long = 123
-    }
 }
 
diff --git a/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/models/Order.kt b/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/models/Order.kt
index 79dce95e1e47..a75a759f7a93 100644
--- a/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/models/Order.kt
+++ b/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/models/Order.kt
@@ -12,7 +12,7 @@
 package org.openapitools.server.models
 
 
-import java.io.Serializable
+import kotlinx.serialization.Serializable
 /**
  * An order for a pets from the pet store
  * @param id 
@@ -22,6 +22,7 @@ import java.io.Serializable
  * @param status Order Status
  * @param complete 
  */
+@Serializable
 data class Order(
     val id: kotlin.Long? = null,
     val petId: kotlin.Long? = null,
@@ -30,11 +31,8 @@ data class Order(
     /* Order Status */
     val status: Order.Status? = null,
     val complete: kotlin.Boolean? = false
-) : Serializable 
+)
 {
-    companion object {
-        private const val serialVersionUID: Long = 123
-    }
     /**
     * Order Status
     * Values: placed,approved,delivered
diff --git a/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/models/Pet.kt b/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/models/Pet.kt
index 8b98ce0469c5..8fe934cc3ff3 100644
--- a/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/models/Pet.kt
+++ b/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/models/Pet.kt
@@ -14,7 +14,7 @@ package org.openapitools.server.models
 import org.openapitools.server.models.Category
 import org.openapitools.server.models.Tag
 
-import java.io.Serializable
+import kotlinx.serialization.Serializable
 /**
  * A pet for sale in the pet store
  * @param name 
@@ -24,6 +24,7 @@ import java.io.Serializable
  * @param tags 
  * @param status pet status in the store
  */
+@Serializable
 data class Pet(
     val name: kotlin.String,
     val photoUrls: kotlin.collections.List<kotlin.String>,
@@ -32,11 +33,8 @@ data class Pet(
     val tags: kotlin.collections.List<Tag>? = null,
     /* pet status in the store */
     val status: Pet.Status? = null
-) : Serializable 
+)
 {
-    companion object {
-        private const val serialVersionUID: Long = 123
-    }
     /**
     * pet status in the store
     * Values: available,pending,sold
diff --git a/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/models/Tag.kt b/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/models/Tag.kt
index e9626b25c6d1..fae4d9d0ba3c 100644
--- a/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/models/Tag.kt
+++ b/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/models/Tag.kt
@@ -12,19 +12,17 @@
 package org.openapitools.server.models
 
 
-import java.io.Serializable
+import kotlinx.serialization.Serializable
 /**
  * A tag for a pet
  * @param id 
  * @param name 
  */
+@Serializable
 data class Tag(
     val id: kotlin.Long? = null,
     val name: kotlin.String? = null
-) : Serializable 
+)
 {
-    companion object {
-        private const val serialVersionUID: Long = 123
-    }
 }
 
diff --git a/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/models/User.kt b/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/models/User.kt
index fdbdb4e1cff4..af04fd61c1cf 100644
--- a/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/models/User.kt
+++ b/samples/server/petstore/kotlin-server/ktor2/src/main/kotlin/org/openapitools/server/models/User.kt
@@ -12,7 +12,7 @@
 package org.openapitools.server.models
 
 
-import java.io.Serializable
+import kotlinx.serialization.Serializable
 /**
  * A User who is purchasing from the pet store
  * @param id 
@@ -24,6 +24,7 @@ import java.io.Serializable
  * @param phone 
  * @param userStatus User Status
  */
+@Serializable
 data class User(
     val id: kotlin.Long? = null,
     val username: kotlin.String? = null,
@@ -34,10 +35,7 @@ data class User(
     val phone: kotlin.String? = null,
     /* User Status */
     val userStatus: kotlin.Int? = null
-) : Serializable 
+)
 {
-    companion object {
-        private const val serialVersionUID: Long = 123
-    }
 }