diff --git a/bin/configs/kotlin-jvm-spring-3-webclient-echo-api.yaml b/bin/configs/kotlin-jvm-spring-3-webclient-echo-api.yaml
index ddafa03ed68..ac7972643cd 100644
--- a/bin/configs/kotlin-jvm-spring-3-webclient-echo-api.yaml
+++ b/bin/configs/kotlin-jvm-spring-3-webclient-echo-api.yaml
@@ -1,6 +1,6 @@
 generatorName: kotlin
 outputDir: samples/client/echo_api/kotlin-jvm-spring-3-webclient
-library: jvm-spring-restclient
+library: jvm-spring-webclient
 inputSpec: modules/openapi-generator/src/test/resources/3_0/kotlin/echo_api.yaml
 templateDir: modules/openapi-generator/src/main/resources/kotlin-client
 additionalProperties:
diff --git a/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-spring-restclient/api.mustache b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-spring-restclient/api.mustache
index 35b33e9d029..7af6f39c4eb 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-spring-restclient/api.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/jvm-spring-restclient/api.mustache
@@ -67,7 +67,7 @@ import {{packageName}}.infrastructure.*
     @Deprecated(message = "This operation is deprecated.")
     {{/isDeprecated}}
     fun {{operationId}}({{#allParams}}{{{paramName}}}: {{#isEnum}}{{#isContainer}}kotlin.collections.List<{{enumName}}{{operationIdCamelCase}}>{{/isContainer}}{{^isContainer}}{{enumName}}{{operationIdCamelCase}}{{/isContainer}}{{/isEnum}}{{^isEnum}}{{{dataType}}}{{/isEnum}}{{^required}}?{{#defaultValue}} = {{>param_default_value}}{{/defaultValue}}{{^defaultValue}} = null{{/defaultValue}}{{/required}}{{^-last}}, {{/-last}}{{/allParams}}): {{#returnType}}{{{returnType}}}{{#nullableReturnType}}?{{/nullableReturnType}}{{/returnType}}{{^returnType}}Unit{{/returnType}} {
-        val result = {{operationId}}WithHttpInfo({{#allParams}}{{{paramName}}} = {{{paramName}}}{{^-last}}, {{/-last}}{{/allParams}})
+        {{#returnType}}val result = {{/returnType}}{{operationId}}WithHttpInfo({{#allParams}}{{{paramName}}} = {{{paramName}}}{{^-last}}, {{/-last}}{{/allParams}})
         {{#returnType}}
         return result.body!!
         {{/returnType}}
diff --git a/samples/client/echo_api/kotlin-jvm-spring-3-webclient/build.gradle b/samples/client/echo_api/kotlin-jvm-spring-3-webclient/build.gradle
index 2e7658f2f33..81441fc10fa 100644
--- a/samples/client/echo_api/kotlin-jvm-spring-3-webclient/build.gradle
+++ b/samples/client/echo_api/kotlin-jvm-spring-3-webclient/build.gradle
@@ -9,6 +9,7 @@ wrapper {
 buildscript {
     ext.kotlin_version = '1.8.10'
     ext.spring_boot_version = "3.2.4"
+    ext.reactor_version = "3.6.4"
     // 6.13.0 is the latest stable release that supports JDK8
     ext.spotless_version = "6.13.0"
 
@@ -59,11 +60,13 @@ kotlin {
         languageVersion.set(JavaLanguageVersion.of(17))
     }
 }
+
 dependencies {
     implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
     implementation "org.jetbrains.kotlin:kotlin-reflect:$kotlin_version"
     implementation "com.fasterxml.jackson.module:jackson-module-kotlin:2.17.0"
     implementation "com.fasterxml.jackson.datatype:jackson-datatype-jsr310:2.17.0"
-    implementation "org.springframework.boot:spring-boot-starter-web:$spring_boot_version"
+    implementation "org.springframework.boot:spring-boot-starter-webflux:$spring_boot_version"
+    implementation "io.projectreactor:reactor-core:$reactor_version"
     testImplementation "io.kotlintest:kotlintest-runner-junit5:3.4.2"
 }
diff --git a/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/AuthApi.kt b/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/AuthApi.kt
index cc3e26512b0..1b274175268 100644
--- a/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/AuthApi.kt
+++ b/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/AuthApi.kt
@@ -17,33 +17,37 @@ package org.openapitools.client.apis
 
 import com.fasterxml.jackson.annotation.JsonProperty
 
-import org.springframework.web.client.RestClient
-import org.springframework.web.client.RestClientResponseException
-
-import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter
+import org.springframework.web.reactive.function.client.WebClient
+import org.springframework.web.reactive.function.client.WebClientResponseException
+import org.springframework.http.codec.json.Jackson2JsonDecoder
+import org.springframework.http.codec.json.Jackson2JsonEncoder
 import org.springframework.http.ResponseEntity
 import org.springframework.http.MediaType
-
+import reactor.core.publisher.Mono
+import org.springframework.util.LinkedMultiValueMap
 
 import org.openapitools.client.infrastructure.*
 
-class AuthApi(client: RestClient) : ApiClient(client) {
+class AuthApi(client: WebClient) : ApiClient(client) {
 
-    constructor(baseUrl: String) : this(RestClient.builder()
+    constructor(baseUrl: String) : this(WebClient.builder()
         .baseUrl(baseUrl)
-        .messageConverters { it.add(MappingJackson2HttpMessageConverter()) }
+        .codecs {
+            it.defaultCodecs().jackson2JsonEncoder(Jackson2JsonEncoder(Serializer.jacksonObjectMapper, MediaType.APPLICATION_JSON))
+            it.defaultCodecs().jackson2JsonDecoder(Jackson2JsonDecoder(Serializer.jacksonObjectMapper, MediaType.APPLICATION_JSON))
+        }
         .build()
     )
 
 
-    @Throws(RestClientResponseException::class)
-    fun testAuthHttpBasic(): kotlin.String {
-        val result = testAuthHttpBasicWithHttpInfo()
-        return result.body!!
+    @Throws(WebClientResponseException::class)
+    fun testAuthHttpBasic(): Mono<kotlin.String> {
+        return testAuthHttpBasicWithHttpInfo()
+            .map { it.body }
     }
 
-    @Throws(RestClientResponseException::class)
-    fun testAuthHttpBasicWithHttpInfo(): ResponseEntity<kotlin.String> {
+    @Throws(WebClientResponseException::class)
+    fun testAuthHttpBasicWithHttpInfo(): Mono<ResponseEntity<kotlin.String>> {
         val localVariableConfig = testAuthHttpBasicRequestConfig()
         return request<Unit, kotlin.String>(
             localVariableConfig
@@ -71,14 +75,14 @@ class AuthApi(client: RestClient) : ApiClient(client) {
     }
 
 
-    @Throws(RestClientResponseException::class)
-    fun testAuthHttpBearer(): kotlin.String {
-        val result = testAuthHttpBearerWithHttpInfo()
-        return result.body!!
+    @Throws(WebClientResponseException::class)
+    fun testAuthHttpBearer(): Mono<kotlin.String> {
+        return testAuthHttpBearerWithHttpInfo()
+            .map { it.body }
     }
 
-    @Throws(RestClientResponseException::class)
-    fun testAuthHttpBearerWithHttpInfo(): ResponseEntity<kotlin.String> {
+    @Throws(WebClientResponseException::class)
+    fun testAuthHttpBearerWithHttpInfo(): Mono<ResponseEntity<kotlin.String>> {
         val localVariableConfig = testAuthHttpBearerRequestConfig()
         return request<Unit, kotlin.String>(
             localVariableConfig
diff --git a/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/BodyApi.kt b/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/BodyApi.kt
index 44ca769307d..49d9a5840be 100644
--- a/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/BodyApi.kt
+++ b/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/BodyApi.kt
@@ -17,35 +17,39 @@ package org.openapitools.client.apis
 
 import com.fasterxml.jackson.annotation.JsonProperty
 
-import org.springframework.web.client.RestClient
-import org.springframework.web.client.RestClientResponseException
-
-import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter
+import org.springframework.web.reactive.function.client.WebClient
+import org.springframework.web.reactive.function.client.WebClientResponseException
+import org.springframework.http.codec.json.Jackson2JsonDecoder
+import org.springframework.http.codec.json.Jackson2JsonEncoder
 import org.springframework.http.ResponseEntity
 import org.springframework.http.MediaType
-
+import reactor.core.publisher.Mono
+import org.springframework.util.LinkedMultiValueMap
 
 import org.openapitools.client.models.Pet
 import org.openapitools.client.models.Tag
 import org.openapitools.client.infrastructure.*
 
-class BodyApi(client: RestClient) : ApiClient(client) {
+class BodyApi(client: WebClient) : ApiClient(client) {
 
-    constructor(baseUrl: String) : this(RestClient.builder()
+    constructor(baseUrl: String) : this(WebClient.builder()
         .baseUrl(baseUrl)
-        .messageConverters { it.add(MappingJackson2HttpMessageConverter()) }
+        .codecs {
+            it.defaultCodecs().jackson2JsonEncoder(Jackson2JsonEncoder(Serializer.jacksonObjectMapper, MediaType.APPLICATION_JSON))
+            it.defaultCodecs().jackson2JsonDecoder(Jackson2JsonDecoder(Serializer.jacksonObjectMapper, MediaType.APPLICATION_JSON))
+        }
         .build()
     )
 
 
-    @Throws(RestClientResponseException::class)
-    fun testBinaryGif(): java.io.File {
-        val result = testBinaryGifWithHttpInfo()
-        return result.body!!
+    @Throws(WebClientResponseException::class)
+    fun testBinaryGif(): Mono<java.io.File> {
+        return testBinaryGifWithHttpInfo()
+            .map { it.body }
     }
 
-    @Throws(RestClientResponseException::class)
-    fun testBinaryGifWithHttpInfo(): ResponseEntity<java.io.File> {
+    @Throws(WebClientResponseException::class)
+    fun testBinaryGifWithHttpInfo(): Mono<ResponseEntity<java.io.File>> {
         val localVariableConfig = testBinaryGifRequestConfig()
         return request<Unit, java.io.File>(
             localVariableConfig
@@ -73,14 +77,14 @@ class BodyApi(client: RestClient) : ApiClient(client) {
     }
 
 
-    @Throws(RestClientResponseException::class)
-    fun testBodyApplicationOctetstreamBinary(body: java.io.File? = null): kotlin.String {
-        val result = testBodyApplicationOctetstreamBinaryWithHttpInfo(body = body)
-        return result.body!!
+    @Throws(WebClientResponseException::class)
+    fun testBodyApplicationOctetstreamBinary(body: java.io.File? = null): Mono<kotlin.String> {
+        return testBodyApplicationOctetstreamBinaryWithHttpInfo(body = body)
+            .map { it.body }
     }
 
-    @Throws(RestClientResponseException::class)
-    fun testBodyApplicationOctetstreamBinaryWithHttpInfo(body: java.io.File? = null): ResponseEntity<kotlin.String> {
+    @Throws(WebClientResponseException::class)
+    fun testBodyApplicationOctetstreamBinaryWithHttpInfo(body: java.io.File? = null): Mono<ResponseEntity<kotlin.String>> {
         val localVariableConfig = testBodyApplicationOctetstreamBinaryRequestConfig(body = body)
         return request<java.io.File, kotlin.String>(
             localVariableConfig
@@ -109,14 +113,14 @@ class BodyApi(client: RestClient) : ApiClient(client) {
     }
 
 
-    @Throws(RestClientResponseException::class)
-    fun testBodyMultipartFormdataArrayOfBinary(files: kotlin.collections.List<java.io.File>): kotlin.String {
-        val result = testBodyMultipartFormdataArrayOfBinaryWithHttpInfo(files = files)
-        return result.body!!
+    @Throws(WebClientResponseException::class)
+    fun testBodyMultipartFormdataArrayOfBinary(files: kotlin.collections.List<java.io.File>): Mono<kotlin.String> {
+        return testBodyMultipartFormdataArrayOfBinaryWithHttpInfo(files = files)
+            .map { it.body }
     }
 
-    @Throws(RestClientResponseException::class)
-    fun testBodyMultipartFormdataArrayOfBinaryWithHttpInfo(files: kotlin.collections.List<java.io.File>): ResponseEntity<kotlin.String> {
+    @Throws(WebClientResponseException::class)
+    fun testBodyMultipartFormdataArrayOfBinaryWithHttpInfo(files: kotlin.collections.List<java.io.File>): Mono<ResponseEntity<kotlin.String>> {
         val localVariableConfig = testBodyMultipartFormdataArrayOfBinaryRequestConfig(files = files)
         return request<Map<String, PartConfig<*>>, kotlin.String>(
             localVariableConfig
@@ -145,14 +149,14 @@ class BodyApi(client: RestClient) : ApiClient(client) {
     }
 
 
-    @Throws(RestClientResponseException::class)
-    fun testBodyMultipartFormdataSingleBinary(myFile: java.io.File? = null): kotlin.String {
-        val result = testBodyMultipartFormdataSingleBinaryWithHttpInfo(myFile = myFile)
-        return result.body!!
+    @Throws(WebClientResponseException::class)
+    fun testBodyMultipartFormdataSingleBinary(myFile: java.io.File? = null): Mono<kotlin.String> {
+        return testBodyMultipartFormdataSingleBinaryWithHttpInfo(myFile = myFile)
+            .map { it.body }
     }
 
-    @Throws(RestClientResponseException::class)
-    fun testBodyMultipartFormdataSingleBinaryWithHttpInfo(myFile: java.io.File? = null): ResponseEntity<kotlin.String> {
+    @Throws(WebClientResponseException::class)
+    fun testBodyMultipartFormdataSingleBinaryWithHttpInfo(myFile: java.io.File? = null): Mono<ResponseEntity<kotlin.String>> {
         val localVariableConfig = testBodyMultipartFormdataSingleBinaryRequestConfig(myFile = myFile)
         return request<Map<String, PartConfig<*>>, kotlin.String>(
             localVariableConfig
@@ -181,14 +185,14 @@ class BodyApi(client: RestClient) : ApiClient(client) {
     }
 
 
-    @Throws(RestClientResponseException::class)
-    fun testEchoBodyFreeFormObjectResponseString(body: kotlin.Any? = null): kotlin.String {
-        val result = testEchoBodyFreeFormObjectResponseStringWithHttpInfo(body = body)
-        return result.body!!
+    @Throws(WebClientResponseException::class)
+    fun testEchoBodyFreeFormObjectResponseString(body: kotlin.Any? = null): Mono<kotlin.String> {
+        return testEchoBodyFreeFormObjectResponseStringWithHttpInfo(body = body)
+            .map { it.body }
     }
 
-    @Throws(RestClientResponseException::class)
-    fun testEchoBodyFreeFormObjectResponseStringWithHttpInfo(body: kotlin.Any? = null): ResponseEntity<kotlin.String> {
+    @Throws(WebClientResponseException::class)
+    fun testEchoBodyFreeFormObjectResponseStringWithHttpInfo(body: kotlin.Any? = null): Mono<ResponseEntity<kotlin.String>> {
         val localVariableConfig = testEchoBodyFreeFormObjectResponseStringRequestConfig(body = body)
         return request<kotlin.Any, kotlin.String>(
             localVariableConfig
@@ -217,14 +221,14 @@ class BodyApi(client: RestClient) : ApiClient(client) {
     }
 
 
-    @Throws(RestClientResponseException::class)
-    fun testEchoBodyPet(pet: Pet? = null): Pet {
-        val result = testEchoBodyPetWithHttpInfo(pet = pet)
-        return result.body!!
+    @Throws(WebClientResponseException::class)
+    fun testEchoBodyPet(pet: Pet? = null): Mono<Pet> {
+        return testEchoBodyPetWithHttpInfo(pet = pet)
+            .map { it.body }
     }
 
-    @Throws(RestClientResponseException::class)
-    fun testEchoBodyPetWithHttpInfo(pet: Pet? = null): ResponseEntity<Pet> {
+    @Throws(WebClientResponseException::class)
+    fun testEchoBodyPetWithHttpInfo(pet: Pet? = null): Mono<ResponseEntity<Pet>> {
         val localVariableConfig = testEchoBodyPetRequestConfig(pet = pet)
         return request<Pet, Pet>(
             localVariableConfig
@@ -253,14 +257,14 @@ class BodyApi(client: RestClient) : ApiClient(client) {
     }
 
 
-    @Throws(RestClientResponseException::class)
-    fun testEchoBodyPetResponseString(pet: Pet? = null): kotlin.String {
-        val result = testEchoBodyPetResponseStringWithHttpInfo(pet = pet)
-        return result.body!!
+    @Throws(WebClientResponseException::class)
+    fun testEchoBodyPetResponseString(pet: Pet? = null): Mono<kotlin.String> {
+        return testEchoBodyPetResponseStringWithHttpInfo(pet = pet)
+            .map { it.body }
     }
 
-    @Throws(RestClientResponseException::class)
-    fun testEchoBodyPetResponseStringWithHttpInfo(pet: Pet? = null): ResponseEntity<kotlin.String> {
+    @Throws(WebClientResponseException::class)
+    fun testEchoBodyPetResponseStringWithHttpInfo(pet: Pet? = null): Mono<ResponseEntity<kotlin.String>> {
         val localVariableConfig = testEchoBodyPetResponseStringRequestConfig(pet = pet)
         return request<Pet, kotlin.String>(
             localVariableConfig
@@ -289,14 +293,14 @@ class BodyApi(client: RestClient) : ApiClient(client) {
     }
 
 
-    @Throws(RestClientResponseException::class)
-    fun testEchoBodyTagResponseString(tag: Tag? = null): kotlin.String {
-        val result = testEchoBodyTagResponseStringWithHttpInfo(tag = tag)
-        return result.body!!
+    @Throws(WebClientResponseException::class)
+    fun testEchoBodyTagResponseString(tag: Tag? = null): Mono<kotlin.String> {
+        return testEchoBodyTagResponseStringWithHttpInfo(tag = tag)
+            .map { it.body }
     }
 
-    @Throws(RestClientResponseException::class)
-    fun testEchoBodyTagResponseStringWithHttpInfo(tag: Tag? = null): ResponseEntity<kotlin.String> {
+    @Throws(WebClientResponseException::class)
+    fun testEchoBodyTagResponseStringWithHttpInfo(tag: Tag? = null): Mono<ResponseEntity<kotlin.String>> {
         val localVariableConfig = testEchoBodyTagResponseStringRequestConfig(tag = tag)
         return request<Tag, kotlin.String>(
             localVariableConfig
diff --git a/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/FormApi.kt b/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/FormApi.kt
index c45ae1a23b6..7182da46e83 100644
--- a/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/FormApi.kt
+++ b/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/FormApi.kt
@@ -17,33 +17,37 @@ package org.openapitools.client.apis
 
 import com.fasterxml.jackson.annotation.JsonProperty
 
-import org.springframework.web.client.RestClient
-import org.springframework.web.client.RestClientResponseException
-
-import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter
+import org.springframework.web.reactive.function.client.WebClient
+import org.springframework.web.reactive.function.client.WebClientResponseException
+import org.springframework.http.codec.json.Jackson2JsonDecoder
+import org.springframework.http.codec.json.Jackson2JsonEncoder
 import org.springframework.http.ResponseEntity
 import org.springframework.http.MediaType
-
+import reactor.core.publisher.Mono
+import org.springframework.util.LinkedMultiValueMap
 
 import org.openapitools.client.infrastructure.*
 
-class FormApi(client: RestClient) : ApiClient(client) {
+class FormApi(client: WebClient) : ApiClient(client) {
 
-    constructor(baseUrl: String) : this(RestClient.builder()
+    constructor(baseUrl: String) : this(WebClient.builder()
         .baseUrl(baseUrl)
-        .messageConverters { it.add(MappingJackson2HttpMessageConverter()) }
+        .codecs {
+            it.defaultCodecs().jackson2JsonEncoder(Jackson2JsonEncoder(Serializer.jacksonObjectMapper, MediaType.APPLICATION_JSON))
+            it.defaultCodecs().jackson2JsonDecoder(Jackson2JsonDecoder(Serializer.jacksonObjectMapper, MediaType.APPLICATION_JSON))
+        }
         .build()
     )
 
 
-    @Throws(RestClientResponseException::class)
-    fun testFormIntegerBooleanString(integerForm: kotlin.Int? = null, booleanForm: kotlin.Boolean? = null, stringForm: kotlin.String? = null): kotlin.String {
-        val result = testFormIntegerBooleanStringWithHttpInfo(integerForm = integerForm, booleanForm = booleanForm, stringForm = stringForm)
-        return result.body!!
+    @Throws(WebClientResponseException::class)
+    fun testFormIntegerBooleanString(integerForm: kotlin.Int? = null, booleanForm: kotlin.Boolean? = null, stringForm: kotlin.String? = null): Mono<kotlin.String> {
+        return testFormIntegerBooleanStringWithHttpInfo(integerForm = integerForm, booleanForm = booleanForm, stringForm = stringForm)
+            .map { it.body }
     }
 
-    @Throws(RestClientResponseException::class)
-    fun testFormIntegerBooleanStringWithHttpInfo(integerForm: kotlin.Int? = null, booleanForm: kotlin.Boolean? = null, stringForm: kotlin.String? = null): ResponseEntity<kotlin.String> {
+    @Throws(WebClientResponseException::class)
+    fun testFormIntegerBooleanStringWithHttpInfo(integerForm: kotlin.Int? = null, booleanForm: kotlin.Boolean? = null, stringForm: kotlin.String? = null): Mono<ResponseEntity<kotlin.String>> {
         val localVariableConfig = testFormIntegerBooleanStringRequestConfig(integerForm = integerForm, booleanForm = booleanForm, stringForm = stringForm)
         return request<Map<String, PartConfig<*>>, kotlin.String>(
             localVariableConfig
@@ -74,14 +78,14 @@ class FormApi(client: RestClient) : ApiClient(client) {
     }
 
 
-    @Throws(RestClientResponseException::class)
-    fun testFormOneof(form1: kotlin.String? = null, form2: kotlin.Int? = null, form3: kotlin.String? = null, form4: kotlin.Boolean? = null, id: kotlin.Long? = null, name: kotlin.String? = null): kotlin.String {
-        val result = testFormOneofWithHttpInfo(form1 = form1, form2 = form2, form3 = form3, form4 = form4, id = id, name = name)
-        return result.body!!
+    @Throws(WebClientResponseException::class)
+    fun testFormOneof(form1: kotlin.String? = null, form2: kotlin.Int? = null, form3: kotlin.String? = null, form4: kotlin.Boolean? = null, id: kotlin.Long? = null, name: kotlin.String? = null): Mono<kotlin.String> {
+        return testFormOneofWithHttpInfo(form1 = form1, form2 = form2, form3 = form3, form4 = form4, id = id, name = name)
+            .map { it.body }
     }
 
-    @Throws(RestClientResponseException::class)
-    fun testFormOneofWithHttpInfo(form1: kotlin.String? = null, form2: kotlin.Int? = null, form3: kotlin.String? = null, form4: kotlin.Boolean? = null, id: kotlin.Long? = null, name: kotlin.String? = null): ResponseEntity<kotlin.String> {
+    @Throws(WebClientResponseException::class)
+    fun testFormOneofWithHttpInfo(form1: kotlin.String? = null, form2: kotlin.Int? = null, form3: kotlin.String? = null, form4: kotlin.Boolean? = null, id: kotlin.Long? = null, name: kotlin.String? = null): Mono<ResponseEntity<kotlin.String>> {
         val localVariableConfig = testFormOneofRequestConfig(form1 = form1, form2 = form2, form3 = form3, form4 = form4, id = id, name = name)
         return request<Map<String, PartConfig<*>>, kotlin.String>(
             localVariableConfig
diff --git a/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/HeaderApi.kt b/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/HeaderApi.kt
index ce7a48355e8..b21a449f903 100644
--- a/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/HeaderApi.kt
+++ b/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/HeaderApi.kt
@@ -17,22 +17,26 @@ package org.openapitools.client.apis
 
 import com.fasterxml.jackson.annotation.JsonProperty
 
-import org.springframework.web.client.RestClient
-import org.springframework.web.client.RestClientResponseException
-
-import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter
+import org.springframework.web.reactive.function.client.WebClient
+import org.springframework.web.reactive.function.client.WebClientResponseException
+import org.springframework.http.codec.json.Jackson2JsonDecoder
+import org.springframework.http.codec.json.Jackson2JsonEncoder
 import org.springframework.http.ResponseEntity
 import org.springframework.http.MediaType
-
+import reactor.core.publisher.Mono
+import org.springframework.util.LinkedMultiValueMap
 
 import org.openapitools.client.models.StringEnumRef
 import org.openapitools.client.infrastructure.*
 
-class HeaderApi(client: RestClient) : ApiClient(client) {
+class HeaderApi(client: WebClient) : ApiClient(client) {
 
-    constructor(baseUrl: String) : this(RestClient.builder()
+    constructor(baseUrl: String) : this(WebClient.builder()
         .baseUrl(baseUrl)
-        .messageConverters { it.add(MappingJackson2HttpMessageConverter()) }
+        .codecs {
+            it.defaultCodecs().jackson2JsonEncoder(Jackson2JsonEncoder(Serializer.jacksonObjectMapper, MediaType.APPLICATION_JSON))
+            it.defaultCodecs().jackson2JsonDecoder(Jackson2JsonDecoder(Serializer.jacksonObjectMapper, MediaType.APPLICATION_JSON))
+        }
         .build()
     )
 
@@ -46,14 +50,14 @@ class HeaderApi(client: RestClient) : ApiClient(client) {
     }
 
 
-    @Throws(RestClientResponseException::class)
-    fun testHeaderIntegerBooleanStringEnums(integerHeader: kotlin.Int? = null, booleanHeader: kotlin.Boolean? = null, stringHeader: kotlin.String? = null, enumNonrefStringHeader: EnumNonrefStringHeaderTestHeaderIntegerBooleanStringEnums? = null, enumRefStringHeader: StringEnumRef? = null): kotlin.String {
-        val result = testHeaderIntegerBooleanStringEnumsWithHttpInfo(integerHeader = integerHeader, booleanHeader = booleanHeader, stringHeader = stringHeader, enumNonrefStringHeader = enumNonrefStringHeader, enumRefStringHeader = enumRefStringHeader)
-        return result.body!!
+    @Throws(WebClientResponseException::class)
+    fun testHeaderIntegerBooleanStringEnums(integerHeader: kotlin.Int? = null, booleanHeader: kotlin.Boolean? = null, stringHeader: kotlin.String? = null, enumNonrefStringHeader: EnumNonrefStringHeaderTestHeaderIntegerBooleanStringEnums? = null, enumRefStringHeader: StringEnumRef? = null): Mono<kotlin.String> {
+        return testHeaderIntegerBooleanStringEnumsWithHttpInfo(integerHeader = integerHeader, booleanHeader = booleanHeader, stringHeader = stringHeader, enumNonrefStringHeader = enumNonrefStringHeader, enumRefStringHeader = enumRefStringHeader)
+            .map { it.body }
     }
 
-    @Throws(RestClientResponseException::class)
-    fun testHeaderIntegerBooleanStringEnumsWithHttpInfo(integerHeader: kotlin.Int? = null, booleanHeader: kotlin.Boolean? = null, stringHeader: kotlin.String? = null, enumNonrefStringHeader: EnumNonrefStringHeaderTestHeaderIntegerBooleanStringEnums? = null, enumRefStringHeader: StringEnumRef? = null): ResponseEntity<kotlin.String> {
+    @Throws(WebClientResponseException::class)
+    fun testHeaderIntegerBooleanStringEnumsWithHttpInfo(integerHeader: kotlin.Int? = null, booleanHeader: kotlin.Boolean? = null, stringHeader: kotlin.String? = null, enumNonrefStringHeader: EnumNonrefStringHeaderTestHeaderIntegerBooleanStringEnums? = null, enumRefStringHeader: StringEnumRef? = null): Mono<ResponseEntity<kotlin.String>> {
         val localVariableConfig = testHeaderIntegerBooleanStringEnumsRequestConfig(integerHeader = integerHeader, booleanHeader = booleanHeader, stringHeader = stringHeader, enumNonrefStringHeader = enumNonrefStringHeader, enumRefStringHeader = enumRefStringHeader)
         return request<Unit, kotlin.String>(
             localVariableConfig
diff --git a/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/PathApi.kt b/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/PathApi.kt
index f1af5bd244a..062e0a6c403 100644
--- a/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/PathApi.kt
+++ b/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/PathApi.kt
@@ -17,22 +17,26 @@ package org.openapitools.client.apis
 
 import com.fasterxml.jackson.annotation.JsonProperty
 
-import org.springframework.web.client.RestClient
-import org.springframework.web.client.RestClientResponseException
-
-import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter
+import org.springframework.web.reactive.function.client.WebClient
+import org.springframework.web.reactive.function.client.WebClientResponseException
+import org.springframework.http.codec.json.Jackson2JsonDecoder
+import org.springframework.http.codec.json.Jackson2JsonEncoder
 import org.springframework.http.ResponseEntity
 import org.springframework.http.MediaType
-
+import reactor.core.publisher.Mono
+import org.springframework.util.LinkedMultiValueMap
 
 import org.openapitools.client.models.StringEnumRef
 import org.openapitools.client.infrastructure.*
 
-class PathApi(client: RestClient) : ApiClient(client) {
+class PathApi(client: WebClient) : ApiClient(client) {
 
-    constructor(baseUrl: String) : this(RestClient.builder()
+    constructor(baseUrl: String) : this(WebClient.builder()
         .baseUrl(baseUrl)
-        .messageConverters { it.add(MappingJackson2HttpMessageConverter()) }
+        .codecs {
+            it.defaultCodecs().jackson2JsonEncoder(Jackson2JsonEncoder(Serializer.jacksonObjectMapper, MediaType.APPLICATION_JSON))
+            it.defaultCodecs().jackson2JsonDecoder(Jackson2JsonDecoder(Serializer.jacksonObjectMapper, MediaType.APPLICATION_JSON))
+        }
         .build()
     )
 
@@ -46,14 +50,14 @@ class PathApi(client: RestClient) : ApiClient(client) {
     }
 
 
-    @Throws(RestClientResponseException::class)
-    fun testsPathStringPathStringIntegerPathIntegerEnumNonrefStringPathEnumRefStringPath(pathString: kotlin.String, pathInteger: kotlin.Int, enumNonrefStringPath: EnumNonrefStringPathTestsPathStringPathStringIntegerPathIntegerEnumNonrefStringPathEnumRefStringPath, enumRefStringPath: StringEnumRef): kotlin.String {
-        val result = testsPathStringPathStringIntegerPathIntegerEnumNonrefStringPathEnumRefStringPathWithHttpInfo(pathString = pathString, pathInteger = pathInteger, enumNonrefStringPath = enumNonrefStringPath, enumRefStringPath = enumRefStringPath)
-        return result.body!!
+    @Throws(WebClientResponseException::class)
+    fun testsPathStringPathStringIntegerPathIntegerEnumNonrefStringPathEnumRefStringPath(pathString: kotlin.String, pathInteger: kotlin.Int, enumNonrefStringPath: EnumNonrefStringPathTestsPathStringPathStringIntegerPathIntegerEnumNonrefStringPathEnumRefStringPath, enumRefStringPath: StringEnumRef): Mono<kotlin.String> {
+        return testsPathStringPathStringIntegerPathIntegerEnumNonrefStringPathEnumRefStringPathWithHttpInfo(pathString = pathString, pathInteger = pathInteger, enumNonrefStringPath = enumNonrefStringPath, enumRefStringPath = enumRefStringPath)
+            .map { it.body }
     }
 
-    @Throws(RestClientResponseException::class)
-    fun testsPathStringPathStringIntegerPathIntegerEnumNonrefStringPathEnumRefStringPathWithHttpInfo(pathString: kotlin.String, pathInteger: kotlin.Int, enumNonrefStringPath: EnumNonrefStringPathTestsPathStringPathStringIntegerPathIntegerEnumNonrefStringPathEnumRefStringPath, enumRefStringPath: StringEnumRef): ResponseEntity<kotlin.String> {
+    @Throws(WebClientResponseException::class)
+    fun testsPathStringPathStringIntegerPathIntegerEnumNonrefStringPathEnumRefStringPathWithHttpInfo(pathString: kotlin.String, pathInteger: kotlin.Int, enumNonrefStringPath: EnumNonrefStringPathTestsPathStringPathStringIntegerPathIntegerEnumNonrefStringPathEnumRefStringPath, enumRefStringPath: StringEnumRef): Mono<ResponseEntity<kotlin.String>> {
         val localVariableConfig = testsPathStringPathStringIntegerPathIntegerEnumNonrefStringPathEnumRefStringPathRequestConfig(pathString = pathString, pathInteger = pathInteger, enumNonrefStringPath = enumNonrefStringPath, enumRefStringPath = enumRefStringPath)
         return request<Unit, kotlin.String>(
             localVariableConfig
diff --git a/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/QueryApi.kt b/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/QueryApi.kt
index 3b2b78ffec9..dc2d0bb902d 100644
--- a/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/QueryApi.kt
+++ b/samples/client/echo_api/kotlin-jvm-spring-3-webclient/src/main/kotlin/org/openapitools/client/apis/QueryApi.kt
@@ -17,24 +17,28 @@ package org.openapitools.client.apis
 
 import com.fasterxml.jackson.annotation.JsonProperty
 
-import org.springframework.web.client.RestClient
-import org.springframework.web.client.RestClientResponseException
-
-import org.springframework.http.converter.json.MappingJackson2HttpMessageConverter
+import org.springframework.web.reactive.function.client.WebClient
+import org.springframework.web.reactive.function.client.WebClientResponseException
+import org.springframework.http.codec.json.Jackson2JsonDecoder
+import org.springframework.http.codec.json.Jackson2JsonEncoder
 import org.springframework.http.ResponseEntity
 import org.springframework.http.MediaType
-
+import reactor.core.publisher.Mono
+import org.springframework.util.LinkedMultiValueMap
 
 import org.openapitools.client.models.Pet
 import org.openapitools.client.models.StringEnumRef
 import org.openapitools.client.models.TestQueryStyleFormExplodeTrueArrayStringQueryObjectParameter
 import org.openapitools.client.infrastructure.*
 
-class QueryApi(client: RestClient) : ApiClient(client) {
+class QueryApi(client: WebClient) : ApiClient(client) {
 
-    constructor(baseUrl: String) : this(RestClient.builder()
+    constructor(baseUrl: String) : this(WebClient.builder()
         .baseUrl(baseUrl)
-        .messageConverters { it.add(MappingJackson2HttpMessageConverter()) }
+        .codecs {
+            it.defaultCodecs().jackson2JsonEncoder(Jackson2JsonEncoder(Serializer.jacksonObjectMapper, MediaType.APPLICATION_JSON))
+            it.defaultCodecs().jackson2JsonDecoder(Jackson2JsonDecoder(Serializer.jacksonObjectMapper, MediaType.APPLICATION_JSON))
+        }
         .build()
     )
 
@@ -48,14 +52,14 @@ class QueryApi(client: RestClient) : ApiClient(client) {
     }
 
 
-    @Throws(RestClientResponseException::class)
-    fun testEnumRefString(enumNonrefStringQuery: EnumNonrefStringQueryTestEnumRefString? = null, enumRefStringQuery: StringEnumRef? = null): kotlin.String {
-        val result = testEnumRefStringWithHttpInfo(enumNonrefStringQuery = enumNonrefStringQuery, enumRefStringQuery = enumRefStringQuery)
-        return result.body!!
+    @Throws(WebClientResponseException::class)
+    fun testEnumRefString(enumNonrefStringQuery: EnumNonrefStringQueryTestEnumRefString? = null, enumRefStringQuery: StringEnumRef? = null): Mono<kotlin.String> {
+        return testEnumRefStringWithHttpInfo(enumNonrefStringQuery = enumNonrefStringQuery, enumRefStringQuery = enumRefStringQuery)
+            .map { it.body }
     }
 
-    @Throws(RestClientResponseException::class)
-    fun testEnumRefStringWithHttpInfo(enumNonrefStringQuery: EnumNonrefStringQueryTestEnumRefString? = null, enumRefStringQuery: StringEnumRef? = null): ResponseEntity<kotlin.String> {
+    @Throws(WebClientResponseException::class)
+    fun testEnumRefStringWithHttpInfo(enumNonrefStringQuery: EnumNonrefStringQueryTestEnumRefString? = null, enumRefStringQuery: StringEnumRef? = null): Mono<ResponseEntity<kotlin.String>> {
         val localVariableConfig = testEnumRefStringRequestConfig(enumNonrefStringQuery = enumNonrefStringQuery, enumRefStringQuery = enumRefStringQuery)
         return request<Unit, kotlin.String>(
             localVariableConfig
@@ -91,14 +95,14 @@ class QueryApi(client: RestClient) : ApiClient(client) {
     }
 
 
-    @Throws(RestClientResponseException::class)
-    fun testQueryDatetimeDateString(datetimeQuery: java.time.OffsetDateTime? = null, dateQuery: java.time.LocalDate? = null, stringQuery: kotlin.String? = null): kotlin.String {
-        val result = testQueryDatetimeDateStringWithHttpInfo(datetimeQuery = datetimeQuery, dateQuery = dateQuery, stringQuery = stringQuery)
-        return result.body!!
+    @Throws(WebClientResponseException::class)
+    fun testQueryDatetimeDateString(datetimeQuery: java.time.OffsetDateTime? = null, dateQuery: java.time.LocalDate? = null, stringQuery: kotlin.String? = null): Mono<kotlin.String> {
+        return testQueryDatetimeDateStringWithHttpInfo(datetimeQuery = datetimeQuery, dateQuery = dateQuery, stringQuery = stringQuery)
+            .map { it.body }
     }
 
-    @Throws(RestClientResponseException::class)
-    fun testQueryDatetimeDateStringWithHttpInfo(datetimeQuery: java.time.OffsetDateTime? = null, dateQuery: java.time.LocalDate? = null, stringQuery: kotlin.String? = null): ResponseEntity<kotlin.String> {
+    @Throws(WebClientResponseException::class)
+    fun testQueryDatetimeDateStringWithHttpInfo(datetimeQuery: java.time.OffsetDateTime? = null, dateQuery: java.time.LocalDate? = null, stringQuery: kotlin.String? = null): Mono<ResponseEntity<kotlin.String>> {
         val localVariableConfig = testQueryDatetimeDateStringRequestConfig(datetimeQuery = datetimeQuery, dateQuery = dateQuery, stringQuery = stringQuery)
         return request<Unit, kotlin.String>(
             localVariableConfig
@@ -137,14 +141,14 @@ class QueryApi(client: RestClient) : ApiClient(client) {
     }
 
 
-    @Throws(RestClientResponseException::class)
-    fun testQueryIntegerBooleanString(integerQuery: kotlin.Int? = null, booleanQuery: kotlin.Boolean? = null, stringQuery: kotlin.String? = null): kotlin.String {
-        val result = testQueryIntegerBooleanStringWithHttpInfo(integerQuery = integerQuery, booleanQuery = booleanQuery, stringQuery = stringQuery)
-        return result.body!!
+    @Throws(WebClientResponseException::class)
+    fun testQueryIntegerBooleanString(integerQuery: kotlin.Int? = null, booleanQuery: kotlin.Boolean? = null, stringQuery: kotlin.String? = null): Mono<kotlin.String> {
+        return testQueryIntegerBooleanStringWithHttpInfo(integerQuery = integerQuery, booleanQuery = booleanQuery, stringQuery = stringQuery)
+            .map { it.body }
     }
 
-    @Throws(RestClientResponseException::class)
-    fun testQueryIntegerBooleanStringWithHttpInfo(integerQuery: kotlin.Int? = null, booleanQuery: kotlin.Boolean? = null, stringQuery: kotlin.String? = null): ResponseEntity<kotlin.String> {
+    @Throws(WebClientResponseException::class)
+    fun testQueryIntegerBooleanStringWithHttpInfo(integerQuery: kotlin.Int? = null, booleanQuery: kotlin.Boolean? = null, stringQuery: kotlin.String? = null): Mono<ResponseEntity<kotlin.String>> {
         val localVariableConfig = testQueryIntegerBooleanStringRequestConfig(integerQuery = integerQuery, booleanQuery = booleanQuery, stringQuery = stringQuery)
         return request<Unit, kotlin.String>(
             localVariableConfig
@@ -183,14 +187,14 @@ class QueryApi(client: RestClient) : ApiClient(client) {
     }
 
 
-    @Throws(RestClientResponseException::class)
-    fun testQueryStyleDeepObjectExplodeTrueObject(queryObject: Pet? = null): kotlin.String {
-        val result = testQueryStyleDeepObjectExplodeTrueObjectWithHttpInfo(queryObject = queryObject)
-        return result.body!!
+    @Throws(WebClientResponseException::class)
+    fun testQueryStyleDeepObjectExplodeTrueObject(queryObject: Pet? = null): Mono<kotlin.String> {
+        return testQueryStyleDeepObjectExplodeTrueObjectWithHttpInfo(queryObject = queryObject)
+            .map { it.body }
     }
 
-    @Throws(RestClientResponseException::class)
-    fun testQueryStyleDeepObjectExplodeTrueObjectWithHttpInfo(queryObject: Pet? = null): ResponseEntity<kotlin.String> {
+    @Throws(WebClientResponseException::class)
+    fun testQueryStyleDeepObjectExplodeTrueObjectWithHttpInfo(queryObject: Pet? = null): Mono<ResponseEntity<kotlin.String>> {
         val localVariableConfig = testQueryStyleDeepObjectExplodeTrueObjectRequestConfig(queryObject = queryObject)
         return request<Unit, kotlin.String>(
             localVariableConfig
@@ -223,14 +227,14 @@ class QueryApi(client: RestClient) : ApiClient(client) {
     }
 
 
-    @Throws(RestClientResponseException::class)
-    fun testQueryStyleFormExplodeTrueArrayString(queryObject: TestQueryStyleFormExplodeTrueArrayStringQueryObjectParameter? = null): kotlin.String {
-        val result = testQueryStyleFormExplodeTrueArrayStringWithHttpInfo(queryObject = queryObject)
-        return result.body!!
+    @Throws(WebClientResponseException::class)
+    fun testQueryStyleFormExplodeTrueArrayString(queryObject: TestQueryStyleFormExplodeTrueArrayStringQueryObjectParameter? = null): Mono<kotlin.String> {
+        return testQueryStyleFormExplodeTrueArrayStringWithHttpInfo(queryObject = queryObject)
+            .map { it.body }
     }
 
-    @Throws(RestClientResponseException::class)
-    fun testQueryStyleFormExplodeTrueArrayStringWithHttpInfo(queryObject: TestQueryStyleFormExplodeTrueArrayStringQueryObjectParameter? = null): ResponseEntity<kotlin.String> {
+    @Throws(WebClientResponseException::class)
+    fun testQueryStyleFormExplodeTrueArrayStringWithHttpInfo(queryObject: TestQueryStyleFormExplodeTrueArrayStringQueryObjectParameter? = null): Mono<ResponseEntity<kotlin.String>> {
         val localVariableConfig = testQueryStyleFormExplodeTrueArrayStringRequestConfig(queryObject = queryObject)
         return request<Unit, kotlin.String>(
             localVariableConfig
@@ -263,14 +267,14 @@ class QueryApi(client: RestClient) : ApiClient(client) {
     }
 
 
-    @Throws(RestClientResponseException::class)
-    fun testQueryStyleFormExplodeTrueObject(queryObject: Pet? = null): kotlin.String {
-        val result = testQueryStyleFormExplodeTrueObjectWithHttpInfo(queryObject = queryObject)
-        return result.body!!
+    @Throws(WebClientResponseException::class)
+    fun testQueryStyleFormExplodeTrueObject(queryObject: Pet? = null): Mono<kotlin.String> {
+        return testQueryStyleFormExplodeTrueObjectWithHttpInfo(queryObject = queryObject)
+            .map { it.body }
     }
 
-    @Throws(RestClientResponseException::class)
-    fun testQueryStyleFormExplodeTrueObjectWithHttpInfo(queryObject: Pet? = null): ResponseEntity<kotlin.String> {
+    @Throws(WebClientResponseException::class)
+    fun testQueryStyleFormExplodeTrueObjectWithHttpInfo(queryObject: Pet? = null): Mono<ResponseEntity<kotlin.String>> {
         val localVariableConfig = testQueryStyleFormExplodeTrueObjectRequestConfig(queryObject = queryObject)
         return request<Unit, kotlin.String>(
             localVariableConfig
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 64f843ed93b..b8acccd3de1 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
@@ -4,13 +4,14 @@ import org.springframework.core.ParameterizedTypeReference
 import org.springframework.http.HttpHeaders
 import org.springframework.http.HttpMethod
 import org.springframework.http.MediaType
-import org.springframework.web.client.RestClient
+import org.springframework.web.reactive.function.client.WebClient
 import org.springframework.http.ResponseEntity
 import org.springframework.util.LinkedMultiValueMap
+import reactor.core.publisher.Mono
 
-open class ApiClient(protected val client: RestClient) {
+open class ApiClient(protected val client: WebClient) {
 
-    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>): Mono<ResponseEntity<T>> {
         return prepare(defaults(requestConfig))
             .retrieve()
             .toEntity(object : ParameterizedTypeReference<T>() {})
@@ -20,7 +21,7 @@ open class ApiClient(protected val client: RestClient) {
         client.method(requestConfig)
             .uri(requestConfig)
             .headers(requestConfig)
-            .nullableBody(requestConfig)
+            .body(requestConfig)
 
     protected fun <I> defaults(requestConfig: RequestConfig<I>) =
         requestConfig.apply {
@@ -32,10 +33,10 @@ open class ApiClient(protected val client: RestClient) {
             }
         }
 
-    private fun <I> RestClient.method(requestConfig: RequestConfig<I>)=
+    private fun <I> WebClient.method(requestConfig: RequestConfig<I>)=
         method(HttpMethod.valueOf(requestConfig.method.name))
 
-    private fun <I> RestClient.RequestBodyUriSpec.uri(requestConfig: RequestConfig<I>) =
+    private fun <I> WebClient.RequestBodyUriSpec.uri(requestConfig: RequestConfig<I>) =
         uri { builder ->
             builder
                 .path(requestConfig.path)
@@ -43,11 +44,11 @@ open class ApiClient(protected val client: RestClient) {
                 .build(requestConfig.params)
         }
 
-    private fun <I> RestClient.RequestBodySpec.headers(requestConfig: RequestConfig<I>) =
+    private fun <I> WebClient.RequestBodySpec.headers(requestConfig: RequestConfig<I>) =
         apply { requestConfig.headers.forEach { (name, value) -> header(name, value) } }
 
-    private fun <I : Any> RestClient.RequestBodySpec.nullableBody(requestConfig: RequestConfig<I>) =
-        apply { if (requestConfig.body != null) body(requestConfig.body) }
+    private fun <I : Any> WebClient.RequestBodySpec.body(requestConfig: RequestConfig<I>) =
+        apply { if (requestConfig.body != null) bodyValue(requestConfig.body) }
 }
 
 inline fun <reified T: Any> parseDateToQueryString(value : T): String {
diff --git a/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/apis/PetApi.kt b/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
index a1555520b2c..4f5441e98e5 100644
--- a/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/apis/PetApi.kt
@@ -77,7 +77,7 @@ class PetApi(client: RestClient) : ApiClient(client) {
 
     @Throws(RestClientResponseException::class)
     fun deletePet(petId: kotlin.Long, apiKey: kotlin.String? = null): Unit {
-        val result = deletePetWithHttpInfo(petId = petId, apiKey = apiKey)
+        deletePetWithHttpInfo(petId = petId, apiKey = apiKey)
     }
 
     @Throws(RestClientResponseException::class)
@@ -273,7 +273,7 @@ class PetApi(client: RestClient) : ApiClient(client) {
 
     @Throws(RestClientResponseException::class)
     fun updatePetWithForm(petId: kotlin.Long, name: kotlin.String? = null, status: kotlin.String? = null): Unit {
-        val result = updatePetWithFormWithHttpInfo(petId = petId, name = name, status = status)
+        updatePetWithFormWithHttpInfo(petId = petId, name = name, status = status)
     }
 
     @Throws(RestClientResponseException::class)
diff --git a/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt b/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
index e16a1593944..777a6f9f5e4 100644
--- a/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/apis/StoreApi.kt
@@ -39,7 +39,7 @@ class StoreApi(client: RestClient) : ApiClient(client) {
 
     @Throws(RestClientResponseException::class)
     fun deleteOrder(orderId: kotlin.String): Unit {
-        val result = deleteOrderWithHttpInfo(orderId = orderId)
+        deleteOrderWithHttpInfo(orderId = orderId)
     }
 
     @Throws(RestClientResponseException::class)
diff --git a/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/apis/UserApi.kt b/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
index caa0f6729b6..8d7967a0d70 100644
--- a/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
+++ b/samples/client/petstore/kotlin-jvm-spring-3-restclient/src/main/kotlin/org/openapitools/client/apis/UserApi.kt
@@ -39,7 +39,7 @@ class UserApi(client: RestClient) : ApiClient(client) {
 
     @Throws(RestClientResponseException::class)
     fun createUser(user: User): Unit {
-        val result = createUserWithHttpInfo(user = user)
+        createUserWithHttpInfo(user = user)
     }
 
     @Throws(RestClientResponseException::class)
@@ -73,7 +73,7 @@ class UserApi(client: RestClient) : ApiClient(client) {
 
     @Throws(RestClientResponseException::class)
     fun createUsersWithArrayInput(user: kotlin.collections.List<User>): Unit {
-        val result = createUsersWithArrayInputWithHttpInfo(user = user)
+        createUsersWithArrayInputWithHttpInfo(user = user)
     }
 
     @Throws(RestClientResponseException::class)
@@ -107,7 +107,7 @@ class UserApi(client: RestClient) : ApiClient(client) {
 
     @Throws(RestClientResponseException::class)
     fun createUsersWithListInput(user: kotlin.collections.List<User>): Unit {
-        val result = createUsersWithListInputWithHttpInfo(user = user)
+        createUsersWithListInputWithHttpInfo(user = user)
     }
 
     @Throws(RestClientResponseException::class)
@@ -141,7 +141,7 @@ class UserApi(client: RestClient) : ApiClient(client) {
 
     @Throws(RestClientResponseException::class)
     fun deleteUser(username: kotlin.String): Unit {
-        val result = deleteUserWithHttpInfo(username = username)
+        deleteUserWithHttpInfo(username = username)
     }
 
     @Throws(RestClientResponseException::class)
@@ -250,7 +250,7 @@ class UserApi(client: RestClient) : ApiClient(client) {
 
     @Throws(RestClientResponseException::class)
     fun logoutUser(): Unit {
-        val result = logoutUserWithHttpInfo()
+        logoutUserWithHttpInfo()
     }
 
     @Throws(RestClientResponseException::class)
@@ -283,7 +283,7 @@ class UserApi(client: RestClient) : ApiClient(client) {
 
     @Throws(RestClientResponseException::class)
     fun updateUser(username: kotlin.String, user: User): Unit {
-        val result = updateUserWithHttpInfo(username = username, user = user)
+        updateUserWithHttpInfo(username = username, user = user)
     }
 
     @Throws(RestClientResponseException::class)