[Kotlin] Fix default values (#17937)

* Fixed invalid extraction of response body in kotlin-client jvm-spring-*

* Generated echo-api for kotlin-jvm-spring-3-restclient

* Specific echo-api for Kotlin without allOf/anyOf

* Specific echo-api for Kotlin without allOf/anyOf

* Generated all samples

* Added kotlin-jvm-spring-3-restclient sample to workflow

* Fixed syntax problem

* [kotlin] Fixed multiple problems with default values

* [kotlin] Removed old commented code

* [kotlin] Generated new samples after merge with master

* [kotlin] ensure-up-to-date

samples/client/echo_api/kotlin-jvm-spring-3-webclient/docs/HeaderApi.md

@@ -0,0 +1,64 @@
+# HeaderApi
+
+All URIs are relative to *http://localhost:3000*
+
+Method | HTTP request | Description
+------------- | ------------- | -------------
+[**testHeaderIntegerBooleanStringEnums**](HeaderApi.md#testHeaderIntegerBooleanStringEnums) | **GET** /header/integer/boolean/string/enums | Test header parameter(s)
+
+
+<a id="testHeaderIntegerBooleanStringEnums"></a>
+# **testHeaderIntegerBooleanStringEnums**
+> kotlin.String testHeaderIntegerBooleanStringEnums(integerHeader, booleanHeader, stringHeader, enumNonrefStringHeader, enumRefStringHeader)
+
+Test header parameter(s)
+
+Test header parameter(s)
+
+### Example
+```kotlin
+// Import classes:
+//import org.openapitools.client.infrastructure.*
+//import org.openapitools.client.models.*
+
+val apiInstance = HeaderApi()
+val integerHeader : kotlin.Int = 56 // kotlin.Int | 
+val booleanHeader : kotlin.Boolean = true // kotlin.Boolean | 
+val stringHeader : kotlin.String = stringHeader_example // kotlin.String | 
+val enumNonrefStringHeader : kotlin.String = enumNonrefStringHeader_example // kotlin.String | 
+val enumRefStringHeader : StringEnumRef =  // StringEnumRef | 
+try {
+    val result : kotlin.String = apiInstance.testHeaderIntegerBooleanStringEnums(integerHeader, booleanHeader, stringHeader, enumNonrefStringHeader, enumRefStringHeader)
+    println(result)
+} catch (e: ClientException) {
+    println("4xx response calling HeaderApi#testHeaderIntegerBooleanStringEnums")
+    e.printStackTrace()
+} catch (e: ServerException) {
+    println("5xx response calling HeaderApi#testHeaderIntegerBooleanStringEnums")
+    e.printStackTrace()
+}
+```
+
+### Parameters
+
+Name | Type | Description  | Notes
+------------- | ------------- | ------------- | -------------
+ **integerHeader** | **kotlin.Int**|  | [optional]
+ **booleanHeader** | **kotlin.Boolean**|  | [optional]
+ **stringHeader** | **kotlin.String**|  | [optional]
+ **enumNonrefStringHeader** | **kotlin.String**|  | [optional] [enum: success, failure, unclassified]
+ **enumRefStringHeader** | [**StringEnumRef**](.md)|  | [optional] [enum: success, failure, unclassified]
+
+### Return type
+
+**kotlin.String**
+
+### Authorization
+
+No authorization required
+
+### HTTP request headers
+
+ - **Content-Type**: Not defined
+ - **Accept**: text/plain
+