diff --git a/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-spring-restclient/infrastructure/ApiClient.kt.mustache b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-spring-restclient/infrastructure/ApiClient.kt.mustache
index b35a15f2a74e..c6d11989dcef 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-spring-restclient/infrastructure/ApiClient.kt.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-spring-restclient/infrastructure/ApiClient.kt.mustache
@@ -10,7 +10,7 @@ import org.springframework.util.LinkedMultiValueMap
 
 {{^nonPublicApi}}{{#explicitApi}}public {{/explicitApi}}{{/nonPublicApi}}open class ApiClient(protected val client: RestClient) {
 
-    protected inline fun <reified I : Any, reified T: Any?> request(requestConfig: RequestConfig<I>): ResponseEntity<T> {
+    protected inline fun <reified I : Any, reified T: Any> request(requestConfig: RequestConfig<I>): ResponseEntity<T> {
         return prepare(defaults(requestConfig))
             .retrieve()
             .toEntity(object : ParameterizedTypeReference<T>() {})
diff --git a/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-spring-webclient/infrastructure/ApiClient.kt.mustache b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-spring-webclient/infrastructure/ApiClient.kt.mustache
index 76cc01c1ef22..4cb0d09f4475 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-spring-webclient/infrastructure/ApiClient.kt.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-spring-webclient/infrastructure/ApiClient.kt.mustache
@@ -12,7 +12,7 @@ import reactor.core.publisher.Mono
 
 {{^nonPublicApi}}{{#explicitApi}}public {{/explicitApi}}{{/nonPublicApi}}open class ApiClient(protected val client: WebClient) {
 
-    protected inline fun <reified I : Any, reified T: Any?> request(requestConfig: RequestConfig<I>): Mono<ResponseEntity<T>> {
+    protected inline fun <reified I : Any, reified T: Any> request(requestConfig: RequestConfig<I>): Mono<ResponseEntity<T>> {
         return prepare(defaults(requestConfig))
             .retrieve()
             .toEntity(object : ParameterizedTypeReference<T>() {})
diff --git a/samples/client/echo_api/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt b/samples/client/echo_api/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
index b1675a9ff649..d13aa82aab69 100644
--- a/samples/client/echo_api/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
+++ b/samples/client/echo_api/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
@@ -10,7 +10,7 @@ import org.springframework.util.LinkedMultiValueMap
 
 open class ApiClient(protected val client: RestClient) {
 
-    protected inline fun <reified I : Any, reified T: Any?> request(requestConfig: RequestConfig<I>): ResponseEntity<T> {
+    protected inline fun <reified I : Any, reified T: Any> request(requestConfig: RequestConfig<I>): ResponseEntity<T> {
         return prepare(defaults(requestConfig))
             .retrieve()
             .toEntity(object : ParameterizedTypeReference<T>() {})
diff --git a/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt b/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
index ba18c122dbaa..4268f7a54425 100644
--- a/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
+++ b/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
@@ -12,7 +12,7 @@ import reactor.core.publisher.Mono
 
 open class ApiClient(protected val client: WebClient) {
 
-    protected inline fun <reified I : Any, reified T: Any?> request(requestConfig: RequestConfig<I>): Mono<ResponseEntity<T>> {
+    protected inline fun <reified I : Any, reified T: Any> request(requestConfig: RequestConfig<I>): Mono<ResponseEntity<T>> {
         return prepare(defaults(requestConfig))
             .retrieve()
             .toEntity(object : ParameterizedTypeReference<T>() {})
diff --git a/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt b/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
index ba18c122dbaa..4268f7a54425 100644
--- a/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-2-webclient/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
@@ -12,7 +12,7 @@ import reactor.core.publisher.Mono
 
 open class ApiClient(protected val client: WebClient) {
 
-    protected inline fun <reified I : Any, reified T: Any?> request(requestConfig: RequestConfig<I>): Mono<ResponseEntity<T>> {
+    protected inline fun <reified I : Any, reified T: Any> request(requestConfig: RequestConfig<I>): Mono<ResponseEntity<T>> {
         return prepare(defaults(requestConfig))
             .retrieve()
             .toEntity(object : ParameterizedTypeReference<T>() {})
diff --git a/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt b/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
index b1675a9ff649..d13aa82aab69 100644
--- a/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
@@ -10,7 +10,7 @@ import org.springframework.util.LinkedMultiValueMap
 
 open class ApiClient(protected val client: RestClient) {
 
-    protected inline fun <reified I : Any, reified T: Any?> request(requestConfig: RequestConfig<I>): ResponseEntity<T> {
+    protected inline fun <reified I : Any, reified T: Any> request(requestConfig: RequestConfig<I>): ResponseEntity<T> {
         return prepare(defaults(requestConfig))
             .retrieve()
             .toEntity(object : ParameterizedTypeReference<T>() {})
diff --git a/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt b/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
index ba18c122dbaa..4268f7a54425 100644
--- a/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/infrastructure/ApiClient.kt
@@ -12,7 +12,7 @@ import reactor.core.publisher.Mono
 
 open class ApiClient(protected val client: WebClient) {
 
-    protected inline fun <reified I : Any, reified T: Any?> request(requestConfig: RequestConfig<I>): Mono<ResponseEntity<T>> {
+    protected inline fun <reified I : Any, reified T: Any> request(requestConfig: RequestConfig<I>): Mono<ResponseEntity<T>> {
         return prepare(defaults(requestConfig))
             .retrieve()
             .toEntity(object : ParameterizedTypeReference<T>() {})