diff --git a/modules/openapi-generator/src/main/resources/kotlin-client/libraries/multiplatform/auth/HttpBasicAuth.kt.mustache b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/multiplatform/auth/HttpBasicAuth.kt.mustache
index ef6c5888ae1..26325424e5d 100644
--- a/modules/openapi-generator/src/main/resources/kotlin-client/libraries/multiplatform/auth/HttpBasicAuth.kt.mustache
+++ b/modules/openapi-generator/src/main/resources/kotlin-client/libraries/multiplatform/auth/HttpBasicAuth.kt.mustache
@@ -7,7 +7,7 @@ class HttpBasicAuth : Authentication {
     var username: String? = null
     var password: String? = null
 
-    @InternalAPI
+    @OptIn(InternalAPI::class)
     override fun apply(query: MutableMap<String, List<String>>, headers: MutableMap<String, String>) {
         if (username == null && password == null) return
         val str = (username ?: "") + ":" + (password ?: "")
diff --git a/samples/client/petstore/kotlin-multiplatform/gradle/wrapper/gradle-wrapper.properties b/samples/client/petstore/kotlin-multiplatform/gradle/wrapper/gradle-wrapper.properties
index 6ce793f21e8..a40165ee36c 100644
--- a/samples/client/petstore/kotlin-multiplatform/gradle/wrapper/gradle-wrapper.properties
+++ b/samples/client/petstore/kotlin-multiplatform/gradle/wrapper/gradle-wrapper.properties
@@ -1,5 +1,6 @@
+#Fri Sep 24 10:59:07 CEST 2021
 distributionBase=GRADLE_USER_HOME
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.2-bin.zip
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-6.0-bin.zip
-zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
+zipStoreBase=GRADLE_USER_HOME
diff --git a/samples/client/petstore/kotlin-multiplatform/src/commonMain/kotlin/org/openapitools/client/auth/HttpBasicAuth.kt b/samples/client/petstore/kotlin-multiplatform/src/commonMain/kotlin/org/openapitools/client/auth/HttpBasicAuth.kt
index 5f0a52c1951..40276dbb985 100644
--- a/samples/client/petstore/kotlin-multiplatform/src/commonMain/kotlin/org/openapitools/client/auth/HttpBasicAuth.kt
+++ b/samples/client/petstore/kotlin-multiplatform/src/commonMain/kotlin/org/openapitools/client/auth/HttpBasicAuth.kt
@@ -7,7 +7,7 @@ class HttpBasicAuth : Authentication {
     var username: String? = null
     var password: String? = null
 
-    @InternalAPI
+    @OptIn(InternalAPI::class)
     override fun apply(query: MutableMap<String, List<String>>, headers: MutableMap<String, String>) {
         if (username == null && password == null) return
         val str = (username ?: "") + ":" + (password ?: "")