diff --git a/modules/openapi-generator/src/main/resources/kotlin-spring/apiController.mustache b/modules/openapi-generator/src/main/resources/kotlin-spring/apiController.mustache
index 037b9d93d733..fcbc8cc37bca 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-spring/apiController.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-spring/apiController.mustache
@@ -13,7 +13,7 @@ import java.util.Optional
 class {{classname}}Controller(
         @org.springframework.beans.factory.annotation.Autowired(required = false) delegate: {{classname}}Delegate?
 ) : {{classname}} {
-    private val delegate: {{classname}}Delegate
+    private lateinit var delegate: {{classname}}Delegate
 
     init {
         this.delegate = Optional.ofNullable(delegate).orElse(object : {{classname}}Delegate {})
diff --git a/modules/openapi-generator/src/main/resources/kotlin-vertx-server/apiProxy.mustache b/modules/openapi-generator/src/main/resources/kotlin-vertx-server/apiProxy.mustache
index e689c36f3fd8..31d71455db92 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-vertx-server/apiProxy.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-vertx-server/apiProxy.mustache
@@ -20,7 +20,7 @@ import com.google.gson.Gson
 {{/imports}}
 
 class {{classname}}VertxProxyHandler(private val vertx: Vertx, private val service: {{classname}}, topLevel: Boolean, private val timeoutSeconds: Long) : ProxyHandler() {
-    private val timerID: Long
+    private lateinit var timerID: Long
     private var lastAccessed: Long = 0
     init {
         try {
diff --git a/samples/server/petstore/kotlin-springboot-delegate/src/main/kotlin/org/openapitools/api/PetApiController.kt b/samples/server/petstore/kotlin-springboot-delegate/src/main/kotlin/org/openapitools/api/PetApiController.kt
index ac2e8fb60763..931361743fd4 100644
--- a/samples/server/petstore/kotlin-springboot-delegate/src/main/kotlin/org/openapitools/api/PetApiController.kt
+++ b/samples/server/petstore/kotlin-springboot-delegate/src/main/kotlin/org/openapitools/api/PetApiController.kt
@@ -10,7 +10,7 @@ import java.util.Optional
 class PetApiController(
         @org.springframework.beans.factory.annotation.Autowired(required = false) delegate: PetApiDelegate?
 ) : PetApi {
-    private val delegate: PetApiDelegate
+    private lateinit var delegate: PetApiDelegate
 
     init {
         this.delegate = Optional.ofNullable(delegate).orElse(object : PetApiDelegate {})
diff --git a/samples/server/petstore/kotlin-springboot-delegate/src/main/kotlin/org/openapitools/api/StoreApiController.kt b/samples/server/petstore/kotlin-springboot-delegate/src/main/kotlin/org/openapitools/api/StoreApiController.kt
index 3f52082c4c0e..555c2f196fc7 100644
--- a/samples/server/petstore/kotlin-springboot-delegate/src/main/kotlin/org/openapitools/api/StoreApiController.kt
+++ b/samples/server/petstore/kotlin-springboot-delegate/src/main/kotlin/org/openapitools/api/StoreApiController.kt
@@ -10,7 +10,7 @@ import java.util.Optional
 class StoreApiController(
         @org.springframework.beans.factory.annotation.Autowired(required = false) delegate: StoreApiDelegate?
 ) : StoreApi {
-    private val delegate: StoreApiDelegate
+    private lateinit var delegate: StoreApiDelegate
 
     init {
         this.delegate = Optional.ofNullable(delegate).orElse(object : StoreApiDelegate {})
diff --git a/samples/server/petstore/kotlin-springboot-delegate/src/main/kotlin/org/openapitools/api/UserApiController.kt b/samples/server/petstore/kotlin-springboot-delegate/src/main/kotlin/org/openapitools/api/UserApiController.kt
index a9b1b3300c02..5c8903538c5c 100644
--- a/samples/server/petstore/kotlin-springboot-delegate/src/main/kotlin/org/openapitools/api/UserApiController.kt
+++ b/samples/server/petstore/kotlin-springboot-delegate/src/main/kotlin/org/openapitools/api/UserApiController.kt
@@ -10,7 +10,7 @@ import java.util.Optional
 class UserApiController(
         @org.springframework.beans.factory.annotation.Autowired(required = false) delegate: UserApiDelegate?
 ) : UserApi {
-    private val delegate: UserApiDelegate
+    private lateinit var delegate: UserApiDelegate
 
     init {
         this.delegate = Optional.ofNullable(delegate).orElse(object : UserApiDelegate {})
diff --git a/samples/server/petstore/kotlin-vertx-modelMutable/src/main/kotlin/org/openapitools/server/api/verticle/PetApiVertxProxyHandler.kt b/samples/server/petstore/kotlin-vertx-modelMutable/src/main/kotlin/org/openapitools/server/api/verticle/PetApiVertxProxyHandler.kt
index 644fc1cee83a..05ca5658f485 100644
--- a/samples/server/petstore/kotlin-vertx-modelMutable/src/main/kotlin/org/openapitools/server/api/verticle/PetApiVertxProxyHandler.kt
+++ b/samples/server/petstore/kotlin-vertx-modelMutable/src/main/kotlin/org/openapitools/server/api/verticle/PetApiVertxProxyHandler.kt
@@ -20,7 +20,7 @@ import org.openapitools.server.api.model.ModelApiResponse
 import org.openapitools.server.api.model.Pet
 
 class PetApiVertxProxyHandler(private val vertx: Vertx, private val service: PetApi, topLevel: Boolean, private val timeoutSeconds: Long) : ProxyHandler() {
-    private val timerID: Long
+    private lateinit var timerID: Long
     private var lastAccessed: Long = 0
     init {
         try {
diff --git a/samples/server/petstore/kotlin-vertx-modelMutable/src/main/kotlin/org/openapitools/server/api/verticle/StoreApiVertxProxyHandler.kt b/samples/server/petstore/kotlin-vertx-modelMutable/src/main/kotlin/org/openapitools/server/api/verticle/StoreApiVertxProxyHandler.kt
index 985b9249f56d..a43d60b0619e 100644
--- a/samples/server/petstore/kotlin-vertx-modelMutable/src/main/kotlin/org/openapitools/server/api/verticle/StoreApiVertxProxyHandler.kt
+++ b/samples/server/petstore/kotlin-vertx-modelMutable/src/main/kotlin/org/openapitools/server/api/verticle/StoreApiVertxProxyHandler.kt
@@ -19,7 +19,7 @@ import com.google.gson.Gson
 import org.openapitools.server.api.model.Order
 
 class StoreApiVertxProxyHandler(private val vertx: Vertx, private val service: StoreApi, topLevel: Boolean, private val timeoutSeconds: Long) : ProxyHandler() {
-    private val timerID: Long
+    private lateinit var timerID: Long
     private var lastAccessed: Long = 0
     init {
         try {
diff --git a/samples/server/petstore/kotlin-vertx-modelMutable/src/main/kotlin/org/openapitools/server/api/verticle/UserApiVertxProxyHandler.kt b/samples/server/petstore/kotlin-vertx-modelMutable/src/main/kotlin/org/openapitools/server/api/verticle/UserApiVertxProxyHandler.kt
index beee4405bee1..4ed3ed309b5c 100644
--- a/samples/server/petstore/kotlin-vertx-modelMutable/src/main/kotlin/org/openapitools/server/api/verticle/UserApiVertxProxyHandler.kt
+++ b/samples/server/petstore/kotlin-vertx-modelMutable/src/main/kotlin/org/openapitools/server/api/verticle/UserApiVertxProxyHandler.kt
@@ -19,7 +19,7 @@ import com.google.gson.Gson
 import org.openapitools.server.api.model.User
 
 class UserApiVertxProxyHandler(private val vertx: Vertx, private val service: UserApi, topLevel: Boolean, private val timeoutSeconds: Long) : ProxyHandler() {
-    private val timerID: Long
+    private lateinit var timerID: Long
     private var lastAccessed: Long = 0
     init {
         try {
diff --git a/samples/server/petstore/kotlin/vertx/src/main/kotlin/org/openapitools/server/api/verticle/PetApiVertxProxyHandler.kt b/samples/server/petstore/kotlin/vertx/src/main/kotlin/org/openapitools/server/api/verticle/PetApiVertxProxyHandler.kt
index 644fc1cee83a..05ca5658f485 100644
--- a/samples/server/petstore/kotlin/vertx/src/main/kotlin/org/openapitools/server/api/verticle/PetApiVertxProxyHandler.kt
+++ b/samples/server/petstore/kotlin/vertx/src/main/kotlin/org/openapitools/server/api/verticle/PetApiVertxProxyHandler.kt
@@ -20,7 +20,7 @@ import org.openapitools.server.api.model.ModelApiResponse
 import org.openapitools.server.api.model.Pet
 
 class PetApiVertxProxyHandler(private val vertx: Vertx, private val service: PetApi, topLevel: Boolean, private val timeoutSeconds: Long) : ProxyHandler() {
-    private val timerID: Long
+    private lateinit var timerID: Long
     private var lastAccessed: Long = 0
     init {
         try {
diff --git a/samples/server/petstore/kotlin/vertx/src/main/kotlin/org/openapitools/server/api/verticle/StoreApiVertxProxyHandler.kt b/samples/server/petstore/kotlin/vertx/src/main/kotlin/org/openapitools/server/api/verticle/StoreApiVertxProxyHandler.kt
index 985b9249f56d..a43d60b0619e 100644
--- a/samples/server/petstore/kotlin/vertx/src/main/kotlin/org/openapitools/server/api/verticle/StoreApiVertxProxyHandler.kt
+++ b/samples/server/petstore/kotlin/vertx/src/main/kotlin/org/openapitools/server/api/verticle/StoreApiVertxProxyHandler.kt
@@ -19,7 +19,7 @@ import com.google.gson.Gson
 import org.openapitools.server.api.model.Order
 
 class StoreApiVertxProxyHandler(private val vertx: Vertx, private val service: StoreApi, topLevel: Boolean, private val timeoutSeconds: Long) : ProxyHandler() {
-    private val timerID: Long
+    private lateinit var timerID: Long
     private var lastAccessed: Long = 0
     init {
         try {
diff --git a/samples/server/petstore/kotlin/vertx/src/main/kotlin/org/openapitools/server/api/verticle/UserApiVertxProxyHandler.kt b/samples/server/petstore/kotlin/vertx/src/main/kotlin/org/openapitools/server/api/verticle/UserApiVertxProxyHandler.kt
index beee4405bee1..4ed3ed309b5c 100644
--- a/samples/server/petstore/kotlin/vertx/src/main/kotlin/org/openapitools/server/api/verticle/UserApiVertxProxyHandler.kt
+++ b/samples/server/petstore/kotlin/vertx/src/main/kotlin/org/openapitools/server/api/verticle/UserApiVertxProxyHandler.kt
@@ -19,7 +19,7 @@ import com.google.gson.Gson
 import org.openapitools.server.api.model.User
 
 class UserApiVertxProxyHandler(private val vertx: Vertx, private val service: UserApi, topLevel: Boolean, private val timeoutSeconds: Long) : ProxyHandler() {
-    private val timerID: Long
+    private lateinit var timerID: Long
     private var lastAccessed: Long = 0
     init {
         try {