kotlin specific feature (#1427)

starter-core/src/main/java/io/micronaut/starter/feature/KotlinSpecificFeature.java

@@ -0,0 +1,32 @@
+/*
+ * Copyright 2017-2022 original authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.micronaut.starter.feature;
+
+import io.micronaut.starter.options.Language;
+
+/**
+ * A feature that only works with Kotlin specific language.
+ *
+ * @author Sergio
+ * @since 3.7.0
+ */
+public interface KotlinSpecificFeature extends LanguageSpecificFeature {
+
+    @Override
+    default Language getRequiredLanguage() {
+        return Language.KOTLIN;
+    }
+}

starter-core/src/main/java/io/micronaut/starter/feature/config/Config4k.java

@@ -21,7 +21,7 @@
 import io.micronaut.starter.feature.FeatureContext;
 import io.micronaut.starter.feature.FeaturePhase;
 import io.micronaut.starter.feature.FeaturePredicate;
-import io.micronaut.starter.feature.LanguageSpecificFeature;
+import io.micronaut.starter.feature.KotlinSpecificFeature;
 import io.micronaut.starter.options.Language;
 import io.micronaut.starter.template.Config4kTemplate;
 import io.micronaut.starter.template.Template;
@@ -31,7 +31,7 @@
 import java.util.function.Function;
 
 @Singleton
-public class Config4k implements ConfigurationFeature, LanguageSpecificFeature {
+public class Config4k implements ConfigurationFeature, KotlinSpecificFeature {
 
     private static final String EXTENSION = "conf";
 
@@ -80,11 +80,6 @@ public boolean supports(ApplicationType applicationType) {
         return true;
     }
 
-    @Override
-    public Language getRequiredLanguage() {
-        return Language.KOTLIN;
-    }
-
     @Override
     public Function<Configuration, Template> createTemplate() {
         return (config) -> new Config4kTemplate(config.getFullPath(EXTENSION), config);

starter-core/src/main/java/io/micronaut/starter/feature/kotlin/KotlinExtensionFunctions.java

@@ -23,14 +23,14 @@
 import io.micronaut.starter.feature.Feature;
 import io.micronaut.starter.feature.FeatureContext;
 import io.micronaut.starter.feature.FeaturePredicate;
-import io.micronaut.starter.feature.LanguageSpecificFeature;
+import io.micronaut.starter.feature.KotlinSpecificFeature;
 import io.micronaut.starter.options.Language;
 
 import jakarta.inject.Singleton;
 import java.util.Optional;
 
 @Singleton
-public class KotlinExtensionFunctions implements Feature, LanguageSpecificFeature {
+public class KotlinExtensionFunctions implements Feature, KotlinSpecificFeature {
 
     @Override
     public boolean supports(ApplicationType applicationType) {
@@ -81,9 +81,4 @@ public String getDescription() {
     public String getCategory() {
         return Category.LANGUAGES;
     }
-
-    @Override
-    public Language getRequiredLanguage() {
-        return Language.KOTLIN;
-    }
 }

starter-core/src/main/java/io/micronaut/starter/feature/kotlin/Ktor.java

@@ -24,7 +24,7 @@
 import io.micronaut.starter.feature.Feature;
 import io.micronaut.starter.feature.FeatureContext;
 import io.micronaut.starter.feature.FeaturePredicate;
-import io.micronaut.starter.feature.LanguageSpecificFeature;
+import io.micronaut.starter.feature.KotlinSpecificFeature;
 import io.micronaut.starter.feature.kotlin.templates.applicationKotlin;
 import io.micronaut.starter.feature.kotlin.templates.homeRouteKotlin;
 import io.micronaut.starter.feature.kotlin.templates.jacksonFeatureKotlin;
@@ -39,7 +39,7 @@
 import java.util.Optional;
 
 @Singleton
-public class Ktor implements KotlinApplicationFeature, ThirdPartyServerFeature, LanguageSpecificFeature {
+public class Ktor implements KotlinApplicationFeature, ThirdPartyServerFeature, KotlinSpecificFeature {
 
     @Override
     public boolean supports(ApplicationType applicationType) {
@@ -84,11 +84,6 @@ public String getCategory() {
         return Category.SERVER;
     }
 
-    @Override
-    public Language getRequiredLanguage() {
-        return Language.KOTLIN;
-    }
-
     @Override
     @Nullable
     public String mainClassName(GeneratorContext generatorContext) {