Add Gradle Kotlin DSL support

This commit refactors the existing Groovy DSL writers in order to share
code between the Groovy DSL and Kotlin DSL writers.

See gh-851

initializr-generator-spring/src/main/java/io/spring/initializr/generator/spring/build/BuildProjectGenerationConfiguration.java

@@ -19,6 +19,7 @@ package io.spring.initializr.generator.spring.build;
 import io.spring.initializr.generator.buildsystem.Build;
 import io.spring.initializr.generator.buildsystem.DependencyScope;
 import io.spring.initializr.generator.buildsystem.gradle.GradleBuildSystem;
+import io.spring.initializr.generator.buildsystem.gradle.GradleKtsBuildSystem;
 import io.spring.initializr.generator.buildsystem.maven.MavenBuildSystem;
 import io.spring.initializr.generator.condition.ConditionalOnBuildSystem;
 import io.spring.initializr.generator.condition.ConditionalOnLanguage;
@@ -39,6 +40,7 @@ import org.springframework.context.annotation.Bean;
  * Project generation configuration for projects using any build system.
  *
  * @author Andy Wilkinson
+ * @author Jean-Baptiste Nizet
  */
 @ProjectGenerationConfiguration
 public class BuildProjectGenerationConfiguration {
@@ -70,7 +72,7 @@ public class BuildProjectGenerationConfiguration {
 
 	@Bean
 	@ConditionalOnLanguage(KotlinLanguage.ID)
-	@ConditionalOnBuildSystem(GradleBuildSystem.ID)
+	@ConditionalOnBuildSystem({ GradleBuildSystem.ID, GradleKtsBuildSystem.ID })
 	public KotlinJpaGradleBuildCustomizer kotlinJpaGradleBuildCustomizer(
 			InitializrMetadata metadata, KotlinProjectSettings settings) {
 		return new KotlinJpaGradleBuildCustomizer(metadata, settings);

initializr-generator-spring/src/main/java/io/spring/initializr/generator/spring/build/gradle/GradleBuildProjectContributor.java

@@ -29,11 +29,14 @@ import io.spring.initializr.generator.io.IndentingWriterFactory;
 import io.spring.initializr.generator.project.contributor.ProjectContributor;
 
 /**
- * {@link ProjectContributor} for the project's {@code build.gradle} file.
+ * {@link ProjectContributor} template for the project's {@code build.gradle} or
+ * {@code build.gradle.kts} file. A subclass exists for each DSL.
  *
  * @author Andy Wilkinson
+ * @author Jean-Baptiste Nizet
  */
-public class GradleBuildProjectContributor implements BuildWriter, ProjectContributor {
+public abstract class GradleBuildProjectContributor
+		implements BuildWriter, ProjectContributor {
 
 	private final GradleBuildWriter buildWriter;
 
@@ -41,21 +44,25 @@ public class GradleBuildProjectContributor implements BuildWriter, ProjectContri
 
 	private final IndentingWriterFactory indentingWriterFactory;
 
-	GradleBuildProjectContributor(GradleBuildWriter buildWriter, GradleBuild build,
-			IndentingWriterFactory indentingWriterFactory) {
+	private final String buildFileName;
+
+	protected GradleBuildProjectContributor(GradleBuildWriter buildWriter,
+			GradleBuild build, IndentingWriterFactory indentingWriterFactory,
+			String buildFileName) {
 		this.buildWriter = buildWriter;
 		this.build = build;
 		this.indentingWriterFactory = indentingWriterFactory;
+		this.buildFileName = buildFileName;
 	}
 
 	@Override
-	public void contribute(Path projectRoot) throws IOException {
-		Path buildGradle = Files.createFile(projectRoot.resolve("build.gradle"));
+	public final void contribute(Path projectRoot) throws IOException {
+		Path buildGradle = Files.createFile(projectRoot.resolve(this.buildFileName));
 		writeBuild(Files.newBufferedWriter(buildGradle));
 	}
 
 	@Override
-	public void writeBuild(Writer out) throws IOException {
+	public final void writeBuild(Writer out) throws IOException {
 		try (IndentingWriter writer = this.indentingWriterFactory
 				.createIndentingWriter("gradle", out)) {
 			this.buildWriter.writeTo(writer, this.build);

initializr-generator-spring/src/main/java/io/spring/initializr/generator/spring/build/gradle/GradleProjectGenerationConfiguration.java

@@ -23,7 +23,9 @@ import io.spring.initializr.generator.buildsystem.BuildItemResolver;
 import io.spring.initializr.generator.buildsystem.gradle.Gradle3BuildWriter;
 import io.spring.initializr.generator.buildsystem.gradle.GradleBuild;
 import io.spring.initializr.generator.buildsystem.gradle.GradleBuildSystem;
-import io.spring.initializr.generator.buildsystem.gradle.GradleBuildWriter;
+import io.spring.initializr.generator.buildsystem.gradle.GradleKtsBuildSystem;
+import io.spring.initializr.generator.buildsystem.gradle.GroovyDslGradleBuildWriter;
+import io.spring.initializr.generator.buildsystem.gradle.KotlinDslGradleBuildWriter;
 import io.spring.initializr.generator.condition.ConditionalOnBuildSystem;
 import io.spring.initializr.generator.condition.ConditionalOnLanguage;
 import io.spring.initializr.generator.condition.ConditionalOnPackaging;
@@ -35,6 +37,7 @@ import io.spring.initializr.generator.project.ProjectGenerationConfiguration;
 import io.spring.initializr.generator.project.ResolvedProjectDescription;
 import io.spring.initializr.generator.spring.build.BuildCustomizer;
 import io.spring.initializr.generator.spring.util.LambdaSafe;
+import io.spring.initializr.metadata.InitializrMetadata;
 
 import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.context.annotation.Bean;
@@ -45,9 +48,10 @@ import org.springframework.context.annotation.Configuration;
  * Gradle as its build system.
  *
  * @author Andy Wilkinson
+ * @author Jean-Baptiste Nizet
  */
 @ProjectGenerationConfiguration
-@ConditionalOnBuildSystem(GradleBuildSystem.ID)
+@ConditionalOnBuildSystem({ GradleBuildSystem.ID, GradleKtsBuildSystem.ID })
 public class GradleProjectGenerationConfiguration {
 
 	private final IndentingWriterFactory indentingWriterFactory;
@@ -100,14 +104,24 @@ public class GradleProjectGenerationConfiguration {
 
 	@Bean
 	@ConditionalOnPlatformVersion("2.0.0.M1")
+	@ConditionalOnBuildSystem(GradleBuildSystem.ID)
 	public BuildCustomizer<GradleBuild> applyDependencyManagementPluginContributor() {
 		return (build) -> build.applyPlugin("io.spring.dependency-management");
 	}
 
 	@Bean
+	@ConditionalOnBuildSystem(GradleBuildSystem.ID)
 	public GradleBuildProjectContributor gradleBuildProjectContributor(
-			GradleBuildWriter buildWriter, GradleBuild build) {
-		return new GradleBuildProjectContributor(buildWriter, build,
+			GroovyDslGradleBuildWriter buildWriter, GradleBuild build) {
+		return new GroovyDslGradleBuildProjectContributor(buildWriter, build,
+				this.indentingWriterFactory);
+	}
+
+	@Bean
+	@ConditionalOnBuildSystem(GradleKtsBuildSystem.ID)
+	public KotlinDslGradleBuildProjectContributor gradleKtsBuildProjectContributor(
+			KotlinDslGradleBuildWriter buildWriter, GradleBuild build) {
+		return new KotlinDslGradleBuildProjectContributor(buildWriter, build,
 				this.indentingWriterFactory);
 	}
 
@@ -116,6 +130,7 @@ public class GradleProjectGenerationConfiguration {
 	 */
 	@Configuration
 	@ConditionalOnGradleVersion("3")
+	@ConditionalOnBuildSystem(GradleBuildSystem.ID)
 	static class Gradle3ProjectGenerationConfiguration {
 
 		@Bean
@@ -152,6 +167,7 @@ public class GradleProjectGenerationConfiguration {
 	 */
 	@Configuration
 	@ConditionalOnGradleVersion("4")
+	@ConditionalOnBuildSystem(GradleBuildSystem.ID)
 	static class Gradle4ProjectGenerationConfiguration {
 
 		@Bean
@@ -176,21 +192,23 @@ public class GradleProjectGenerationConfiguration {
 	}
 
 	/**
-	 * Configuration specific to projects using Gradle 4 or 5.
+	 * Configuration specific to projects using Gradle (Groovy DSL) 4 or 5.
 	 */
 	@Configuration
+	@ConditionalOnBuildSystem(GradleBuildSystem.ID)
 	@ConditionalOnGradleVersion({ "4", "5" })
 	static class Gradle4Or5ProjectGenerationConfiguration {
 
 		@Bean
-		public GradleBuildWriter gradleBuildWriter() {
-			return new GradleBuildWriter();
+		public GroovyDslGradleBuildWriter gradleBuildWriter() {
+			return new GroovyDslGradleBuildWriter();
 		}
 
 		@Bean
 		public SettingsGradleProjectContributor settingsGradleProjectContributor(
 				GradleBuild build, IndentingWriterFactory indentingWriterFactory) {
-			return new SettingsGradleProjectContributor(build, indentingWriterFactory);
+			return new GroovyDslSettingsGradleProjectContributor(build,
+					indentingWriterFactory);
 		}
 
 		@Bean
@@ -207,4 +225,38 @@ public class GradleProjectGenerationConfiguration {
 
 	}
 
+	/**
+	 * Configuration specific to projects using Gradle (Kotlin DSL).
+	 */
+	@Configuration
+	@ConditionalOnBuildSystem(GradleKtsBuildSystem.ID)
+	static class GradleKtsProjectGenerationConfiguration {
+
+		@Bean
+		public KotlinDslGradleBuildWriter gradleKtsBuildWriter() {
+			return new KotlinDslGradleBuildWriter();
+		}
+
+		@Bean
+		public KotlinDslSettingsGradleProjectContributor settingsGradleKtsProjectContributor(
+				GradleBuild build, IndentingWriterFactory indentingWriterFactory) {
+			return new KotlinDslSettingsGradleProjectContributor(build,
+					indentingWriterFactory);
+		}
+
+		@Bean
+		public BuildCustomizer<GradleBuild> springBootPluginContributor(
+				ResolvedProjectDescription projectDescription,
+				InitializrMetadata metadata) {
+			return (build) -> {
+				build.addPlugin("org.springframework.boot",
+						projectDescription.getPlatformVersion().toString());
+				build.addPlugin("io.spring.dependency-management",
+						metadata.getConfiguration().getEnv().getGradle()
+								.getDependencyManagementPluginVersion());
+			};
+		}
+
+	}
+
 }

initializr-generator-spring/src/main/java/io/spring/initializr/generator/spring/build/gradle/GroovyDslGradleBuildProjectContributor.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2012-2019 the original author or 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
+ *
+ *      http://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.spring.initializr.generator.spring.build.gradle;
+
+import io.spring.initializr.generator.buildsystem.gradle.GradleBuild;
+import io.spring.initializr.generator.buildsystem.gradle.GroovyDslGradleBuildWriter;
+import io.spring.initializr.generator.io.IndentingWriterFactory;
+import io.spring.initializr.generator.project.contributor.ProjectContributor;
+
+/**
+ * {@link ProjectContributor} for the project's {@code build.gradle} file.
+ *
+ * @author Jean-Baptiste Nizet
+ */
+public class GroovyDslGradleBuildProjectContributor
+		extends GradleBuildProjectContributor {
+
+	GroovyDslGradleBuildProjectContributor(GroovyDslGradleBuildWriter buildWriter,
+			GradleBuild build, IndentingWriterFactory indentingWriterFactory) {
+		super(buildWriter, build, indentingWriterFactory, "build.gradle");
+	}
+
+}

initializr-generator-spring/src/main/java/io/spring/initializr/generator/spring/build/gradle/GroovyDslSettingsGradleProjectContributor.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2012-2019 the original author or 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
+ *
+ *      http://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.spring.initializr.generator.spring.build.gradle;
+
+import io.spring.initializr.generator.buildsystem.gradle.GradleBuild;
+import io.spring.initializr.generator.buildsystem.gradle.GroovyDslGradleSettingsWriter;
+import io.spring.initializr.generator.io.IndentingWriterFactory;
+import io.spring.initializr.generator.project.contributor.ProjectContributor;
+
+/**
+ * {@link ProjectContributor} for the project's {@code settings.gradle} file.
+ *
+ * @author Jean-Baptiste Nizet
+ */
+class GroovyDslSettingsGradleProjectContributor extends SettingsGradleProjectContributor {
+
+	GroovyDslSettingsGradleProjectContributor(GradleBuild build,
+			IndentingWriterFactory indentingWriterFactory) {
+		super(build, indentingWriterFactory, new GroovyDslGradleSettingsWriter(),
+				"settings.gradle");
+	}
+
+}

initializr-generator-spring/src/main/java/io/spring/initializr/generator/spring/build/gradle/KotlinDslGradleBuildProjectContributor.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2012-2019 the original author or 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
+ *
+ *      http://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.spring.initializr.generator.spring.build.gradle;
+
+import io.spring.initializr.generator.buildsystem.gradle.GradleBuild;
+import io.spring.initializr.generator.buildsystem.gradle.KotlinDslGradleBuildWriter;
+import io.spring.initializr.generator.io.IndentingWriterFactory;
+import io.spring.initializr.generator.project.contributor.ProjectContributor;
+
+/**
+ * {@link ProjectContributor} for the project's {@code build.gradle.kts} file.
+ *
+ * @author Jean-Baptiste Nizet
+ */
+public class KotlinDslGradleBuildProjectContributor
+		extends GradleBuildProjectContributor {
+
+	KotlinDslGradleBuildProjectContributor(KotlinDslGradleBuildWriter buildWriter,
+			GradleBuild build, IndentingWriterFactory indentingWriterFactory) {
+		super(buildWriter, build, indentingWriterFactory, "build.gradle.kts");
+	}
+
+}

initializr-generator-spring/src/main/java/io/spring/initializr/generator/spring/build/gradle/KotlinDslSettingsGradleProjectContributor.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2012-2019 the original author or 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
+ *
+ *      http://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.spring.initializr.generator.spring.build.gradle;
+
+import io.spring.initializr.generator.buildsystem.gradle.GradleBuild;
+import io.spring.initializr.generator.buildsystem.gradle.KotlinDslGradleSettingsWriter;
+import io.spring.initializr.generator.io.IndentingWriterFactory;
+import io.spring.initializr.generator.project.contributor.ProjectContributor;
+
+/**
+ * {@link ProjectContributor} for the project's {@code settings.gradle.kts} file.
+ *
+ * @author Jean-Baptiste Nizet
+ */
+class KotlinDslSettingsGradleProjectContributor extends SettingsGradleProjectContributor {
+
+	KotlinDslSettingsGradleProjectContributor(GradleBuild build,
+			IndentingWriterFactory indentingWriterFactory) {
+		super(build, indentingWriterFactory, new KotlinDslGradleSettingsWriter(),
+				"settings.gradle.kts");
+	}
+
+}

initializr-generator-spring/src/main/java/io/spring/initializr/generator/spring/build/gradle/SettingsGradleProjectContributor.java

@@ -27,11 +27,13 @@ import io.spring.initializr.generator.io.IndentingWriterFactory;
 import io.spring.initializr.generator.project.contributor.ProjectContributor;
 
 /**
- * {@link ProjectContributor} for the project's {@code settings.gradle} file.
+ * {@link ProjectContributor} for the project's {@code settings.gradle}
+ * {@code settings.gradle.kts} or file. A subclass exists for each of the DSLs.
  *
  * @author Andy Wilkinson
+ * @author Jean-Baptiste Nizet
  */
-class SettingsGradleProjectContributor implements ProjectContributor {
+abstract class SettingsGradleProjectContributor implements ProjectContributor {
 
 	private final GradleBuild build;
 
@@ -39,16 +41,21 @@ class SettingsGradleProjectContributor implements ProjectContributor {
 
 	private final GradleSettingsWriter settingsWriter;
 
-	SettingsGradleProjectContributor(GradleBuild build,
-			IndentingWriterFactory indentingWriterFactory) {
+	private final String settingsFileName;
+
+	protected SettingsGradleProjectContributor(GradleBuild build,
+			IndentingWriterFactory indentingWriterFactory,
+			GradleSettingsWriter settingsWriter, String settingsFileName) {
 		this.build = build;
 		this.indentingWriterFactory = indentingWriterFactory;
-		this.settingsWriter = new GradleSettingsWriter();
+		this.settingsWriter = settingsWriter;
+		this.settingsFileName = settingsFileName;
 	}
 
 	@Override
-	public void contribute(Path projectRoot) throws IOException {
-		Path settingsGradle = Files.createFile(projectRoot.resolve("settings.gradle"));
+	public final void contribute(Path projectRoot) throws IOException {
+		Path settingsGradle = Files
+				.createFile(projectRoot.resolve(this.settingsFileName));
 		try (IndentingWriter writer = this.indentingWriterFactory.createIndentingWriter(
 				"gradle", Files.newBufferedWriter(settingsGradle))) {
 			this.settingsWriter.writeTo(writer, this.build);

initializr-generator-spring/src/main/java/io/spring/initializr/generator/spring/code/groovy/GroovyProjectGenerationDefaultContributorsConfiguration.java

@@ -20,6 +20,7 @@ import java.lang.reflect.Modifier;
 
 import io.spring.initializr.generator.buildsystem.Build;
 import io.spring.initializr.generator.buildsystem.gradle.GradleBuildSystem;
+import io.spring.initializr.generator.buildsystem.gradle.GradleKtsBuildSystem;
 import io.spring.initializr.generator.buildsystem.maven.MavenBuildSystem;
 import io.spring.initializr.generator.condition.ConditionalOnBuildSystem;
 import io.spring.initializr.generator.condition.ConditionalOnPackaging;
@@ -44,6 +45,7 @@ import org.springframework.context.annotation.Configuration;
  * Default Groovy language contributors.
  *
  * @author Stephane Nicoll
+ * @author Jean-Baptiste Nizet
  */
 @Configuration
 class GroovyProjectGenerationDefaultContributorsConfiguration {
@@ -121,7 +123,7 @@ class GroovyProjectGenerationDefaultContributorsConfiguration {
 	 * Configuration for Groovy projects built with Gradle.
 	 */
 	@Configuration
-	@ConditionalOnBuildSystem(GradleBuildSystem.ID)
+	@ConditionalOnBuildSystem({ GradleBuildSystem.ID, GradleKtsBuildSystem.ID })
 	static class GroovyGradleProjectConfiguration {
 
 		@Bean

initializr-generator-spring/src/main/java/io/spring/initializr/generator/spring/code/kotlin/GroovyDslKotlinGradleBuildCustomizer.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2012-2019 the original author or 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
+ *
+ *      http://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.spring.initializr.generator.spring.code.kotlin;
+
+import java.util.stream.Collectors;
+
+import io.spring.initializr.generator.buildsystem.gradle.GradleBuild.TaskCustomization;
+import io.spring.initializr.generator.spring.build.BuildCustomizer;
+
+/**
+ * {@link BuildCustomizer} for Kotlin projects build with Gradle (Groovy DSL).
+ *
+ * @author Jean-Baptiste Nizet
+ */
+class GroovyDslKotlinGradleBuildCustomizer extends KotlinGradleBuildCustomizer {
+
+	GroovyDslKotlinGradleBuildCustomizer(KotlinProjectSettings kotlinProjectSettings) {
+		super(kotlinProjectSettings);
+	}
+
+	@Override
+	protected void customizeKotlinOptions(TaskCustomization compile) {
+		compile.nested("kotlinOptions", (kotlinOptions) -> {
+			String compilerArgs = this.settings.getCompilerArgs().stream()
+					.map((arg) -> "'" + arg + "'").collect(Collectors.joining(", "));
+			kotlinOptions.set("freeCompilerArgs", "[" + compilerArgs + "]");
+			kotlinOptions.set("jvmTarget", "'" + this.settings.getJvmTarget() + "'");
+		});
+	}
+
+}

initializr-generator-spring/src/main/java/io/spring/initializr/generator/spring/code/kotlin/KotlinDslKotlinGradleBuildCustomizer.java

@@ -0,0 +1,45 @@
+/*
+ * Copyright 2012-2019 the original author or 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
+ *
+ *      http://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.spring.initializr.generator.spring.code.kotlin;
+
+import java.util.stream.Collectors;
+
+import io.spring.initializr.generator.buildsystem.gradle.GradleBuild.TaskCustomization;
+import io.spring.initializr.generator.spring.build.BuildCustomizer;
+
+/**
+ * {@link BuildCustomizer} for Kotlin projects build with Gradle (Kotlin DSL).
+ *
+ * @author Jean-Baptiste Nizet
+ */
+class KotlinDslKotlinGradleBuildCustomizer extends KotlinGradleBuildCustomizer {
+
+	KotlinDslKotlinGradleBuildCustomizer(KotlinProjectSettings kotlinProjectSettings) {
+		super(kotlinProjectSettings);
+	}
+
+	@Override
+	protected void customizeKotlinOptions(TaskCustomization compile) {
+		compile.nested("kotlinOptions", (kotlinOptions) -> {
+			String compilerArgs = this.settings.getCompilerArgs().stream()
+					.map((arg) -> "\"" + arg + "\"").collect(Collectors.joining(", "));
+			kotlinOptions.set("freeCompilerArgs", "listOf(" + compilerArgs + ")");
+			kotlinOptions.set("jvmTarget", "\"" + this.settings.getJvmTarget() + "\"");
+		});
+	}
+
+}

initializr-generator-spring/src/main/java/io/spring/initializr/generator/spring/code/kotlin/KotlinGradleBuildCustomizer.java

@@ -16,41 +16,33 @@
 
 package io.spring.initializr.generator.spring.code.kotlin;
 
-import java.util.stream.Collectors;
-
 import io.spring.initializr.generator.buildsystem.gradle.GradleBuild;
 import io.spring.initializr.generator.buildsystem.gradle.GradleBuild.TaskCustomization;
 import io.spring.initializr.generator.spring.build.BuildCustomizer;
 
 /**
- * {@link BuildCustomizer} for Kotlin projects build with Gradle.
+ * {@link BuildCustomizer} template for Kotlin projects build with Gradle. A subclass
+ * exists for each DSL.
  *
  * @author Andy Wilkinson
  * @author Jean-Baptiste Nizet
  */
-class KotlinGradleBuildCustomizer implements BuildCustomizer<GradleBuild> {
+abstract class KotlinGradleBuildCustomizer implements BuildCustomizer<GradleBuild> {
 
-	private final KotlinProjectSettings settings;
+	protected final KotlinProjectSettings settings;
 
 	KotlinGradleBuildCustomizer(KotlinProjectSettings kotlinProjectSettings) {
 		this.settings = kotlinProjectSettings;
 	}
 
 	@Override
-	public void customize(GradleBuild build) {
+	public final void customize(GradleBuild build) {
 		build.addPlugin("org.jetbrains.kotlin.jvm", this.settings.getVersion());
 		build.addPlugin("org.jetbrains.kotlin.plugin.spring", this.settings.getVersion());
 		build.customizeTasksWithType("org.jetbrains.kotlin.gradle.tasks.KotlinCompile",
 				this::customizeKotlinOptions);
 	}
 
-	private void customizeKotlinOptions(TaskCustomization compile) {
-		compile.nested("kotlinOptions", (kotlinOptions) -> {
-			String compilerArgs = this.settings.getCompilerArgs().stream()
-					.map((arg) -> "'" + arg + "'").collect(Collectors.joining(", "));
-			kotlinOptions.set("freeCompilerArgs", "[" + compilerArgs + "]");
-			kotlinOptions.set("jvmTarget", "'" + this.settings.getJvmTarget() + "'");
-		});
-	}
+	protected abstract void customizeKotlinOptions(TaskCustomization compile);
 
 }

initializr-generator-spring/src/main/java/io/spring/initializr/generator/spring/code/kotlin/KotlinProjectGenerationDefaultContributorsConfiguration.java

@@ -18,6 +18,7 @@ package io.spring.initializr.generator.spring.code.kotlin;
 
 import io.spring.initializr.generator.buildsystem.Build;
 import io.spring.initializr.generator.buildsystem.gradle.GradleBuildSystem;
+import io.spring.initializr.generator.buildsystem.gradle.GradleKtsBuildSystem;
 import io.spring.initializr.generator.buildsystem.maven.MavenBuildSystem;
 import io.spring.initializr.generator.condition.ConditionalOnBuildSystem;
 import io.spring.initializr.generator.condition.ConditionalOnPackaging;
@@ -47,6 +48,7 @@ import org.springframework.context.annotation.Configuration;
  *
  * @author Andy Wilkinson
  * @author Stephane Nicoll
+ * @author Jean-Baptiste Nizet
  */
 @Configuration
 class KotlinProjectGenerationDefaultContributorsConfiguration {
@@ -155,7 +157,7 @@ class KotlinProjectGenerationDefaultContributorsConfiguration {
 	}
 
 	/**
-	 * Configuration for Kotlin projects built with Gradle.
+	 * Configuration for Kotlin projects built with Gradle (Groovy DSL).
 	 *
 	 * @author Andy Wilkinson
 	 */
@@ -166,7 +168,24 @@ class KotlinProjectGenerationDefaultContributorsConfiguration {
 		@Bean
 		public KotlinGradleBuildCustomizer kotlinBuildCustomizer(
 				KotlinProjectSettings kotlinProjectSettings) {
-			return new KotlinGradleBuildCustomizer(kotlinProjectSettings);
+			return new GroovyDslKotlinGradleBuildCustomizer(kotlinProjectSettings);
+		}
+
+	}
+
+	/**
+	 * Configuration for Kotlin projects built with Gradle (Kotlin DSL).
+	 *
+	 * @author Jean-Baptiste Nizet
+	 */
+	@Configuration
+	@ConditionalOnBuildSystem(GradleKtsBuildSystem.ID)
+	static class KotlinGradleKtsProjectConfiguration {
+
+		@Bean
+		public KotlinDslKotlinGradleBuildCustomizer kotlinBuildCustomizer(
+				KotlinProjectSettings kotlinProjectSettings) {
+			return new KotlinDslKotlinGradleBuildCustomizer(kotlinProjectSettings);
 		}
 
 	}

initializr-generator-spring/src/main/java/io/spring/initializr/generator/spring/scm/git/GitProjectGenerationConfiguration.java

@@ -17,6 +17,7 @@
 package io.spring.initializr.generator.spring.scm.git;
 
 import io.spring.initializr.generator.buildsystem.gradle.GradleBuildSystem;
+import io.spring.initializr.generator.buildsystem.gradle.GradleKtsBuildSystem;
 import io.spring.initializr.generator.buildsystem.maven.MavenBuildSystem;
 import io.spring.initializr.generator.condition.ConditionalOnBuildSystem;
 import io.spring.initializr.generator.project.ProjectGenerationConfiguration;
@@ -56,7 +57,7 @@ public class GitProjectGenerationConfiguration {
 	}
 
 	@Bean
-	@ConditionalOnBuildSystem(GradleBuildSystem.ID)
+	@ConditionalOnBuildSystem({ GradleBuildSystem.ID, GradleKtsBuildSystem.ID })
 	public GitIgnoreCustomizer gradleGitIgnoreCustomizer() {
 		return (gitIgnore) -> {
 			gitIgnore.getGeneral().add(".gradle", "/build/",

initializr-generator-spring/src/test/java/io/spring/initializr/generator/spring/build/BuildComplianceTests.java

@@ -20,6 +20,7 @@ import java.util.stream.Stream;
 
 import io.spring.initializr.generator.buildsystem.BuildSystem;
 import io.spring.initializr.generator.buildsystem.gradle.GradleBuildSystem;
+import io.spring.initializr.generator.buildsystem.gradle.GradleKtsBuildSystem;
 import io.spring.initializr.generator.buildsystem.maven.MavenBuildSystem;
 import io.spring.initializr.generator.language.Language;
 import io.spring.initializr.generator.language.groovy.GroovyLanguage;
@@ -45,6 +46,7 @@ import org.springframework.core.io.ClassPathResource;
  * Build compliance tests.
  *
  * @author Stephane Nicoll
+ * @author Jean-Baptiste Nizet
  */
 class BuildComplianceTests extends AbstractComplianceTests {
 
@@ -54,13 +56,19 @@ class BuildComplianceTests extends AbstractComplianceTests {
 
 	private static final Language kotlin = new KotlinLanguage();
 
-	static Stream<Arguments> parameters() {
+	static Stream<Arguments> previousGenerationParameters() {
 		return Stream.of(
 				Arguments.arguments(BuildSystem.forId(MavenBuildSystem.ID), "pom.xml"),
 				Arguments.arguments(BuildSystem.forId(GradleBuildSystem.ID),
 						"build.gradle"));
 	}
 
+	static Stream<Arguments> parameters() {
+		return Stream.concat(previousGenerationParameters(),
+				Stream.of(Arguments.arguments(BuildSystem.forId(GradleKtsBuildSystem.ID),
+						"build.gradle.kts")));
+	}
+
 	@ParameterizedTest
 	@MethodSource("parameters")
 	void currentGenerationJarJava(BuildSystem build, String fileName) {
@@ -117,19 +125,19 @@ class BuildComplianceTests extends AbstractComplianceTests {
 	}
 
 	@ParameterizedTest
-	@MethodSource("parameters")
+	@MethodSource("previousGenerationParameters")
 	void previousGenerationJarJava(BuildSystem build, String fileName) {
 		testPreviousGenerationJar(java, build, fileName);
 	}
 
 	@ParameterizedTest
-	@MethodSource("parameters")
+	@MethodSource("previousGenerationParameters")
 	void previousGenerationJarGroovy(BuildSystem build, String fileName) {
 		testPreviousGenerationJar(groovy, build, fileName);
 	}
 
 	@ParameterizedTest
-	@MethodSource("parameters")
+	@MethodSource("previousGenerationParameters")
 	void previousGenerationJarKotlin(BuildSystem build, String fileName) {
 		testPreviousGenerationJar(kotlin, build, fileName);
 	}

initializr-generator-spring/src/test/java/io/spring/initializr/generator/spring/build/gradle/GradleKtsProjectGenerationConfigurationTests.java

@@ -0,0 +1,163 @@
+/*
+ * Copyright 2012-2019 the original author or 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
+ *
+ *      http://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.spring.initializr.generator.spring.build.gradle;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.List;
+import java.util.stream.Stream;
+
+import io.spring.initializr.generator.buildsystem.Dependency;
+import io.spring.initializr.generator.buildsystem.DependencyScope;
+import io.spring.initializr.generator.buildsystem.gradle.GradleKtsBuildSystem;
+import io.spring.initializr.generator.language.java.JavaLanguage;
+import io.spring.initializr.generator.packaging.war.WarPackaging;
+import io.spring.initializr.generator.project.ProjectDescription;
+import io.spring.initializr.generator.spring.build.BuildProjectGenerationConfiguration;
+import io.spring.initializr.generator.spring.build.BuildWriter;
+import io.spring.initializr.generator.spring.test.InitializrMetadataTestBuilder;
+import io.spring.initializr.generator.test.project.ProjectAssetTester;
+import io.spring.initializr.generator.test.project.ProjectStructure;
+import io.spring.initializr.generator.version.Version;
+import io.spring.initializr.metadata.InitializrMetadata;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import org.springframework.util.StreamUtils;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link GradleProjectGenerationConfiguration} with Kotlin DSL build system.
+ *
+ * @author Jean-Baptiste Nizet
+ */
+class GradleKtsProjectGenerationConfigurationTests {
+
+	private ProjectAssetTester projectTester;
+
+	@BeforeEach
+	void setup(@TempDir Path directory) {
+		this.projectTester = new ProjectAssetTester().withIndentingWriterFactory()
+				.withConfiguration(BuildProjectGenerationConfiguration.class,
+						GradleProjectGenerationConfiguration.class)
+				.withDirectory(directory)
+				.withBean(InitializrMetadata.class,
+						() -> InitializrMetadataTestBuilder.withDefaults().build())
+				.withDescriptionCustomizer((description) -> description
+						.setBuildSystem(new GradleKtsBuildSystem()));
+	}
+
+	static Stream<Arguments> supportedPlatformVersions() {
+		// previous versions use gradle < 5, where Kotlin DSL is not supported
+		return Stream.of(Arguments.arguments("2.1.3.RELEASE"));
+	}
+
+	@ParameterizedTest(name = "Spring Boot {0}")
+	@MethodSource("supportedPlatformVersions")
+	void buildWriterIsContributed(String platformVersion) {
+		ProjectDescription description = new ProjectDescription();
+		description.setPlatformVersion(Version.parse(platformVersion));
+		description.setLanguage(new JavaLanguage());
+		BuildWriter buildWriter = this.projectTester.generate(description,
+				(context) -> context.getBean(BuildWriter.class));
+		assertThat(buildWriter)
+				.isInstanceOf(KotlinDslGradleBuildProjectContributor.class);
+	}
+
+	static Stream<Arguments> gradleWrapperParameters() {
+		return Stream.of(Arguments.arguments("2.1.3.RELEASE", "5.2.1"));
+	}
+
+	@ParameterizedTest(name = "Spring Boot {0}")
+	@MethodSource("gradleWrapperParameters")
+	void gradleWrapperIsContributedWhenGeneratingGradleKtsProject(String platformVersion,
+			String expectedGradleVersion) throws IOException {
+		ProjectDescription description = new ProjectDescription();
+		description.setPlatformVersion(Version.parse(platformVersion));
+		description.setLanguage(new JavaLanguage());
+		ProjectStructure projectStructure = this.projectTester.generate(description);
+		List<String> relativePaths = projectStructure.getRelativePathsOfProjectFiles();
+		assertThat(relativePaths).contains("gradlew", "gradlew.bat",
+				"gradle/wrapper/gradle-wrapper.properties",
+				"gradle/wrapper/gradle-wrapper.jar");
+		try (Stream<String> lines = Files.lines(
+				projectStructure.resolve("gradle/wrapper/gradle-wrapper.properties"))) {
+			assertThat(lines.filter((line) -> line
+					.contains(String.format("gradle-%s-bin.zip", expectedGradleVersion))))
+							.hasSize(1);
+		}
+	}
+
+	@Test
+	void buildDotGradleDotKtsIsContributedWhenGeneratingGradleKtsProject()
+			throws IOException {
+		ProjectDescription description = new ProjectDescription();
+		description.setPlatformVersion(Version.parse("2.1.0.RELEASE"));
+		description.setLanguage(new JavaLanguage("11"));
+		description.addDependency("acme",
+				new Dependency("com.example", "acme", DependencyScope.COMPILE));
+		ProjectStructure projectStructure = this.projectTester.generate(description);
+		List<String> relativePaths = projectStructure.getRelativePathsOfProjectFiles();
+		assertThat(relativePaths).contains("build.gradle.kts");
+		Path path = projectStructure.resolve("build.gradle.kts");
+		String[] lines = readAllLines(path);
+		assertThat(lines).containsExactly("plugins {",
+				"    id(\"org.springframework.boot\") version \"2.1.0.RELEASE\"",
+				"    id(\"io.spring.dependency-management\") version \"1.0.6.RELEASE\"",
+				"    java", "}", "", "group = \"com.example\"",
+				"version = \"0.0.1-SNAPSHOT\"",
+				"java.sourceCompatibility = JavaVersion.VERSION_11", "", "repositories {",
+				"    mavenCentral()", "}", "", "dependencies {",
+				"    implementation(\"org.springframework.boot:spring-boot-starter\")",
+				"    implementation(\"com.example:acme\")",
+				"    testImplementation(\"org.springframework.boot:spring-boot-starter-test\")",
+				"}");
+	}
+
+	@Test
+	void warPluginIsAppliedWhenBuildingProjectThatUsesWarPackaging() throws IOException {
+		ProjectDescription description = new ProjectDescription();
+		description.setPlatformVersion(Version.parse("2.1.0.RELEASE"));
+		description.setLanguage(new JavaLanguage());
+		description.setPackaging(new WarPackaging());
+		ProjectStructure projectStructure = this.projectTester.generate(description);
+		List<String> relativePaths = projectStructure.getRelativePathsOfProjectFiles();
+		assertThat(relativePaths).contains("build.gradle.kts");
+		try (Stream<String> lines = Files
+				.lines(projectStructure.resolve("build.gradle.kts"))) {
+			assertThat(lines.filter((line) -> line.contains("    war"))).hasSize(1);
+		}
+	}
+
+	private static String[] readAllLines(Path file) throws IOException {
+		String content = StreamUtils.copyToString(
+				new FileInputStream(new File(file.toString())), StandardCharsets.UTF_8);
+		String[] lines = content.split("\\r?\\n");
+		assertThat(content).endsWith(System.lineSeparator());
+		return lines;
+	}
+
+}

initializr-generator-spring/src/test/java/io/spring/initializr/generator/spring/build/gradle/GradleProjectGenerationConfigurationTests.java

@@ -46,9 +46,10 @@ import org.junit.jupiter.params.provider.MethodSource;
 import static org.assertj.core.api.Assertions.assertThat;
 
 /**
- * Tests for {@link GradleProjectGenerationConfiguration}.
+ * Tests for {@link GradleProjectGenerationConfiguration} with Groovy DSL build system.
  *
  * @author Stephane Nicoll
+ * @author Jean-Baptiste Nizet
  */
 class GradleProjectGenerationConfigurationTests {
 
@@ -81,6 +82,8 @@ class GradleProjectGenerationConfigurationTests {
 		BuildWriter buildWriter = this.projectTester.generate(description,
 				(context) -> context.getBean(BuildWriter.class));
 		assertThat(buildWriter).isInstanceOf(GradleBuildProjectContributor.class);
+		assertThat(buildWriter)
+				.isNotInstanceOf(KotlinDslGradleBuildProjectContributor.class);
 	}
 
 	static Stream<Arguments> gradleWrapperParameters() {

initializr-generator-spring/src/test/java/io/spring/initializr/generator/spring/build/gradle/GroovyDslGradleBuildProjectContributorTests.java

@@ -22,7 +22,7 @@ import java.nio.file.Path;
 import java.util.List;
 
 import io.spring.initializr.generator.buildsystem.gradle.GradleBuild;
-import io.spring.initializr.generator.buildsystem.gradle.GradleBuildWriter;
+import io.spring.initializr.generator.buildsystem.gradle.GroovyDslGradleBuildWriter;
 import io.spring.initializr.generator.io.IndentingWriterFactory;
 import io.spring.initializr.generator.io.SimpleIndentStrategy;
 import io.spring.initializr.generator.test.io.TextTestUtils;
@@ -32,19 +32,21 @@ import org.junit.jupiter.api.io.TempDir;
 import static org.assertj.core.api.Assertions.assertThat;
 
 /**
- * Tests for {@link GradleBuildProjectContributor}.
+ * Tests for {@link GroovyDslGradleBuildProjectContributor}.
  *
  * @author Andy Wilkinson
  * @author Stephane Nicoll
+ * @author Jean-Baptiste Nizet
  */
-class GradleBuildProjectContributorTests {
+class GroovyDslGradleBuildProjectContributorTests {
 
 	@Test
 	void gradleBuildIsContributedInProjectStructure(@TempDir Path projectDir)
 			throws IOException {
 		GradleBuild build = new GradleBuild();
-		new GradleBuildProjectContributor(new GradleBuildWriter(), build,
-				IndentingWriterFactory.withDefaultSettings()).contribute(projectDir);
+		new GroovyDslGradleBuildProjectContributor(new GroovyDslGradleBuildWriter(),
+				build, IndentingWriterFactory.withDefaultSettings())
+						.contribute(projectDir);
 		Path buildGradle = projectDir.resolve("build.gradle");
 		assertThat(buildGradle).isRegularFile();
 	}
@@ -81,8 +83,8 @@ class GradleBuildProjectContributorTests {
 	private List<String> generateBuild(GradleBuild build,
 			IndentingWriterFactory indentingWriterFactory) throws IOException {
 		StringWriter writer = new StringWriter();
-		new GradleBuildProjectContributor(new GradleBuildWriter(), build,
-				indentingWriterFactory).writeBuild(writer);
+		new GroovyDslGradleBuildProjectContributor(new GroovyDslGradleBuildWriter(),
+				build, indentingWriterFactory).writeBuild(writer);
 		return TextTestUtils.readAllLines(writer.toString());
 	}
 

initializr-generator-spring/src/test/java/io/spring/initializr/generator/spring/build/gradle/GroovyDslSettingsGradleProjectContributorTests.java

@@ -31,11 +31,12 @@ import org.junit.jupiter.api.io.TempDir;
 import static org.assertj.core.api.Assertions.assertThat;
 
 /**
- * Tests for {@link SettingsGradleProjectContributor}.
+ * Tests for {@link GroovyDslSettingsGradleProjectContributor}.
  *
  * @author Andy Wilkinson
+ * @author Jean-Baptiste Nizet
  */
-class SettingsGradleProjectContributorTests {
+class GroovyDslSettingsGradleProjectContributorTests {
 
 	@TempDir
 	Path directory;
@@ -77,7 +78,7 @@ class SettingsGradleProjectContributorTests {
 	private List<String> generateSettings(GradleBuild build,
 			IndentingWriterFactory indentingWriterFactory) throws IOException {
 		Path projectDir = Files.createTempDirectory(this.directory, "project-");
-		new SettingsGradleProjectContributor(build, indentingWriterFactory)
+		new GroovyDslSettingsGradleProjectContributor(build, indentingWriterFactory)
 				.contribute(projectDir);
 		return new ProjectStructure(projectDir).readAllLines("settings.gradle");
 	}

initializr-generator-spring/src/test/java/io/spring/initializr/generator/spring/build/gradle/KotlinDslGradleBuildProjectContributorTests.java

@@ -0,0 +1,85 @@
+/*
+ * Copyright 2012-2019 the original author or 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
+ *
+ *      http://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.spring.initializr.generator.spring.build.gradle;
+
+import java.io.IOException;
+import java.io.StringWriter;
+import java.nio.file.Path;
+import java.util.Arrays;
+import java.util.List;
+
+import io.spring.initializr.generator.buildsystem.gradle.GradleBuild;
+import io.spring.initializr.generator.buildsystem.gradle.KotlinDslGradleBuildWriter;
+import io.spring.initializr.generator.io.IndentingWriterFactory;
+import io.spring.initializr.generator.io.SimpleIndentStrategy;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link KotlinDslGradleBuildProjectContributor}.
+ *
+ * @author Jean-Baptiste Nizet
+ */
+class KotlinDslGradleBuildProjectContributorTests {
+
+	@Test
+	void gradleBuildIsContributedInProjectStructure(@TempDir Path projectDir)
+			throws IOException {
+		GradleBuild build = new GradleBuild();
+		new KotlinDslGradleBuildProjectContributor(new KotlinDslGradleBuildWriter(),
+				build, IndentingWriterFactory.withDefaultSettings())
+						.contribute(projectDir);
+		Path buildGradleKts = projectDir.resolve("build.gradle.kts");
+		assertThat(buildGradleKts).isRegularFile();
+	}
+
+	@Test
+	void gradleBuildIsContributedToProject() throws IOException {
+		GradleBuild build = new GradleBuild();
+		build.setGroup("com.example");
+		build.setVersion("1.0.0-SNAPSHOT");
+		List<String> lines = generateBuild(build);
+		assertThat(lines).containsSequence("group = \"com.example\"",
+				"version = \"1.0.0-SNAPSHOT\"");
+	}
+
+	@Test
+	void gradleBuildIsContributedUsingGradleContentId() throws IOException {
+		IndentingWriterFactory indentingWriterFactory = IndentingWriterFactory
+				.create(new SimpleIndentStrategy("    "), (factory) -> factory
+						.indentingStrategy("gradle", new SimpleIndentStrategy("  ")));
+		GradleBuild build = new GradleBuild();
+		build.addPlugin("java");
+		List<String> lines = generateBuild(build, indentingWriterFactory);
+		assertThat(lines).containsSequence("plugins {", "  java", "}");
+	}
+
+	private List<String> generateBuild(GradleBuild build) throws IOException {
+		return generateBuild(build, IndentingWriterFactory.withDefaultSettings());
+	}
+
+	private List<String> generateBuild(GradleBuild build,
+			IndentingWriterFactory indentingWriterFactory) throws IOException {
+		StringWriter writer = new StringWriter();
+		new KotlinDslGradleBuildProjectContributor(new KotlinDslGradleBuildWriter(),
+				build, indentingWriterFactory).writeBuild(writer);
+		return Arrays.asList(writer.toString().split("\\r?\\n"));
+	}
+
+}

initializr-generator-spring/src/test/java/io/spring/initializr/generator/spring/build/gradle/KotlinDslSettingsGradleProjectContributorTests.java

@@ -0,0 +1,86 @@
+/*
+ * Copyright 2012-2019 the original author or 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
+ *
+ *      http://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.spring.initializr.generator.spring.build.gradle;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.List;
+
+import io.spring.initializr.generator.buildsystem.gradle.GradleBuild;
+import io.spring.initializr.generator.io.IndentingWriterFactory;
+import io.spring.initializr.generator.io.SimpleIndentStrategy;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link KotlinDslSettingsGradleProjectContributor}.
+ *
+ * @author Jean-Baptiste Nizet
+ */
+class KotlinDslSettingsGradleProjectContributorTests {
+
+	@TempDir
+	Path directory;
+
+	@Test
+	void gradleSettingsIsContributedToProject() throws IOException {
+		GradleBuild build = new GradleBuild();
+		build.pluginRepositories().add("maven-central");
+		List<String> lines = generateSettings(build);
+		assertThat(lines).containsSequence("pluginManagement {", "    repositories {",
+				"        mavenCentral()", "        gradlePluginPortal()", "    }", "}");
+	}
+
+	@Test
+	void gradleSettingsIsContributedUsingGradleContentId() throws IOException {
+		IndentingWriterFactory indentingWriterFactory = IndentingWriterFactory
+				.create(new SimpleIndentStrategy("    "), (factory) -> factory
+						.indentingStrategy("gradle", new SimpleIndentStrategy("  ")));
+		GradleBuild build = new GradleBuild();
+		build.pluginRepositories().add("maven-central");
+		List<String> lines = generateSettings(build, indentingWriterFactory);
+		assertThat(lines).containsSequence("pluginManagement {", "  repositories {",
+				"    mavenCentral()", "    gradlePluginPortal()", "  }", "}");
+	}
+
+	@Test
+	void gradleSettingsDoesNotUseRepositories() throws IOException {
+		GradleBuild build = new GradleBuild();
+		build.repositories().add("maven-central");
+		List<String> lines = generateSettings(build);
+		assertThat(lines).containsSequence("pluginManagement {", "    repositories {",
+				"        gradlePluginPortal()", "    }", "}");
+	}
+
+	private List<String> generateSettings(GradleBuild build) throws IOException {
+		return generateSettings(build, IndentingWriterFactory.withDefaultSettings());
+	}
+
+	private List<String> generateSettings(GradleBuild build,
+			IndentingWriterFactory indentingWriterFactory) throws IOException {
+		Path projectDir = Files.createTempDirectory(this.directory, "project-");
+		new KotlinDslSettingsGradleProjectContributor(build, indentingWriterFactory)
+				.contribute(projectDir);
+		Path settingsGradle = projectDir.resolve("settings.gradle.kts");
+		assertThat(settingsGradle).isRegularFile();
+		return Files.readAllLines(settingsGradle);
+	}
+
+}

initializr-generator-spring/src/test/java/io/spring/initializr/generator/spring/code/kotlin/GroovyDslKotlinGradleBuildCustomizerTests.java

@@ -0,0 +1,73 @@
+/*
+ * Copyright 2012-2019 the original author or 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
+ *
+ *      http://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.spring.initializr.generator.spring.code.kotlin;
+
+import io.spring.initializr.generator.buildsystem.gradle.GradleBuild;
+import io.spring.initializr.generator.buildsystem.gradle.GradleBuild.TaskCustomization;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link GroovyDslKotlinGradleBuildCustomizer}.
+ *
+ * @author Andy Wilkinson <<<<<<<
+ * HEAD:initializr-generator-spring/src/test/java/io/spring/initializr/generator/spring/code/kotlin/KotlinGradleBuildCustomizerTests.java
+ * @author Jean-Baptiste Nizet ======= >>>>>>> 7ec6a29a... Configure spring project
+ * generation using Gradle Kotlin
+ * DSL:initializr-generator-spring/src/test/java/io/spring/initializr/generator/spring/code/kotlin/GroovyDslKotlinGradleBuildCustomizerTests.java
+ */
+class GroovyDslKotlinGradleBuildCustomizerTests {
+
+	@Test
+	void kotlinPluginsAreConfigured() {
+		GradleBuild build = new GradleBuild();
+		new GroovyDslKotlinGradleBuildCustomizer(
+				new SimpleKotlinProjectSettings("1.2.70")).customize(build);
+		assertThat(build.getPlugins()).hasSize(2);
+		assertThat(build.getPlugins().get(0).getId())
+				.isEqualTo("org.jetbrains.kotlin.jvm");
+		assertThat(build.getPlugins().get(0).getVersion()).isEqualTo("1.2.70");
+		assertThat(build.getPlugins().get(1).getId())
+				.isEqualTo("org.jetbrains.kotlin.plugin.spring");
+		assertThat(build.getPlugins().get(1).getVersion()).isEqualTo("1.2.70");
+	}
+
+	@Test
+	void kotlinCompilationTasksAreCustomized() {
+		GradleBuild build = new GradleBuild();
+		new GroovyDslKotlinGradleBuildCustomizer(
+				new SimpleKotlinProjectSettings("1.2.70")).customize(build);
+		assertThat(build.getTasksWithTypeCustomizations()).hasSize(1);
+		assertThat(build.getTasksWithTypeCustomizations()).containsKeys("KotlinCompile");
+		assertKotlinOptions(build.getTasksWithTypeCustomizations().get("KotlinCompile"));
+	}
+
+	private void assertKotlinOptions(TaskCustomization compileTask) {
+		assertThat(compileTask.getAssignments()).isEmpty();
+		assertThat(compileTask.getInvocations()).isEmpty();
+		assertThat(compileTask.getNested()).hasSize(1);
+		TaskCustomization kotlinOptions = compileTask.getNested().get("kotlinOptions");
+		assertThat(kotlinOptions.getInvocations()).hasSize(0);
+		assertThat(kotlinOptions.getNested()).hasSize(0);
+		assertThat(kotlinOptions.getAssignments()).hasSize(2);
+		assertThat(kotlinOptions.getAssignments())
+				.containsEntry("freeCompilerArgs", "['-Xjsr305=strict']")
+				.containsEntry("jvmTarget", "'1.8'");
+	}
+
+}

initializr-generator-spring/src/test/java/io/spring/initializr/generator/spring/code/kotlin/KotlinDslKotlinGradleBuildCustomizerTests.java

@@ -23,17 +23,17 @@ import org.junit.jupiter.api.Test;
 import static org.assertj.core.api.Assertions.assertThat;
 
 /**
- * Tests for {@link KotlinGradleBuildCustomizer}.
+ * Tests for {@link KotlinDslKotlinGradleBuildCustomizer}.
  *
- * @author Andy Wilkinson
+ * @author Jean-Baptiste Nizet
  */
-class KotlinGradleBuildCustomizerTests {
+class KotlinDslKotlinGradleBuildCustomizerTests {
 
 	@Test
 	void kotlinPluginsAreConfigured() {
 		GradleBuild build = new GradleBuild();
-		new KotlinGradleBuildCustomizer(new SimpleKotlinProjectSettings("1.2.70"))
-				.customize(build);
+		new KotlinDslKotlinGradleBuildCustomizer(
+				new SimpleKotlinProjectSettings("1.2.70")).customize(build);
 		assertThat(build.getPlugins()).hasSize(2);
 		assertThat(build.getPlugins().get(0).getId())
 				.isEqualTo("org.jetbrains.kotlin.jvm");
@@ -46,10 +46,8 @@ class KotlinGradleBuildCustomizerTests {
 	@Test
 	void kotlinCompilationTasksAreCustomized() {
 		GradleBuild build = new GradleBuild();
-		new KotlinGradleBuildCustomizer(new SimpleKotlinProjectSettings("1.2.70"))
-				.customize(build);
-		assertThat(build.getImportedTypes())
-				.contains("org.jetbrains.kotlin.gradle.tasks.KotlinCompile");
+		new KotlinDslKotlinGradleBuildCustomizer(
+				new SimpleKotlinProjectSettings("1.2.70")).customize(build);
 		assertThat(build.getTasksWithTypeCustomizations()).hasSize(1);
 		assertThat(build.getTasksWithTypeCustomizations()).containsKeys("KotlinCompile");
 		assertKotlinOptions(build.getTasksWithTypeCustomizations().get("KotlinCompile"));
@@ -64,8 +62,8 @@ class KotlinGradleBuildCustomizerTests {
 		assertThat(kotlinOptions.getNested()).hasSize(0);
 		assertThat(kotlinOptions.getAssignments()).hasSize(2);
 		assertThat(kotlinOptions.getAssignments())
-				.containsEntry("freeCompilerArgs", "['-Xjsr305=strict']")
-				.containsEntry("jvmTarget", "'1.8'");
+				.containsEntry("freeCompilerArgs", "listOf(\"-Xjsr305=strict\")")
+				.containsEntry("jvmTarget", "\"1.8\"");
 	}
 
 }

initializr-generator-spring/src/test/java/io/spring/initializr/generator/spring/test/InitializrMetadataTestBuilder.java

@@ -80,7 +80,7 @@ public class InitializrMetadataTestBuilder {
 	}
 
 	public InitializrMetadataTestBuilder addAllDefaults() {
-		return addBasicDefaults().setGradleEnv("0.5.1.RELEASE").setKotlinEnv("1.1.1");
+		return addBasicDefaults().setGradleEnv("1.0.6.RELEASE").setKotlinEnv("1.1.1");
 	}
 
 	public InitializrMetadataTestBuilder addBasicDefaults() {

initializr-generator-spring/src/test/resources/project/gradle-kts/annotation-processor-dependency-build.gradle.kts.gen

@@ -0,0 +1,26 @@
+plugins {
+	id("org.springframework.boot") version "2.1.1.RELEASE"
+	id("io.spring.dependency-management") version "1.0.6.RELEASE"
+	java
+}
+
+group = "com.example"
+version = "0.0.1-SNAPSHOT"
+java.sourceCompatibility = JavaVersion.VERSION_1_8
+
+configurations {
+	compileOnly {
+		extendsFrom(configurations.annotationProcessor.get())
+	}
+}
+
+repositories {
+	mavenCentral()
+}
+
+dependencies {
+	implementation("org.springframework.boot:spring-boot-starter-data-jpa")
+	implementation("org.springframework.boot:spring-boot-starter-web")
+	annotationProcessor("org.springframework.boot:spring-boot-configuration-processor")
+	testImplementation("org.springframework.boot:spring-boot-starter-test")
+}

initializr-generator-spring/src/test/resources/project/gradle-kts/bom-ordering-build.gradle.kts.gen

@@ -0,0 +1,26 @@
+plugins {
+	id("org.springframework.boot") version "2.1.1.RELEASE"
+	id("io.spring.dependency-management") version "1.0.6.RELEASE"
+	java
+}
+
+group = "com.example"
+version = "0.0.1-SNAPSHOT"
+java.sourceCompatibility = JavaVersion.VERSION_1_8
+
+repositories {
+	mavenCentral()
+}
+
+dependencies {
+	implementation("org.acme:foo")
+	testImplementation("org.springframework.boot:spring-boot-starter-test")
+}
+
+dependencyManagement {
+	imports {
+		mavenBom("org.acme:bar-bom:1.0")
+		mavenBom("org.acme:biz-bom:1.0")
+		mavenBom("org.acme:foo-bom:1.0")
+	}
+}

initializr-generator-spring/src/test/resources/project/gradle-kts/bom-property-build.gradle.kts.gen

@@ -0,0 +1,26 @@
+plugins {
+	id("org.springframework.boot") version "2.1.1.RELEASE"
+	id("io.spring.dependency-management") version "1.0.6.RELEASE"
+	java
+}
+
+group = "com.example"
+version = "0.0.1-SNAPSHOT"
+java.sourceCompatibility = JavaVersion.VERSION_1_8
+
+repositories {
+	mavenCentral()
+}
+
+extra["fooVersion"] = "1.3.3"
+
+dependencies {
+	implementation("org.acme:foo")
+	testImplementation("org.springframework.boot:spring-boot-starter-test")
+}
+
+dependencyManagement {
+	imports {
+		mavenBom("org.acme:foo-bom:${fooVersion}")
+	}
+}

initializr-generator-spring/src/test/resources/project/gradle-kts/compile-only-dependency-build.gradle.kts.gen

@@ -0,0 +1,20 @@
+plugins {
+	id("org.springframework.boot") version "2.1.1.RELEASE"
+	id("io.spring.dependency-management") version "1.0.6.RELEASE"
+	java
+}
+
+group = "com.example"
+version = "0.0.1-SNAPSHOT"
+java.sourceCompatibility = JavaVersion.VERSION_1_8
+
+repositories {
+	mavenCentral()
+}
+
+dependencies {
+	implementation("org.springframework.boot:spring-boot-starter-data-jpa")
+	implementation("org.springframework.boot:spring-boot-starter-web")
+	compileOnly("org.acme:foo")
+	testImplementation("org.springframework.boot:spring-boot-starter-test")
+}

initializr-generator-spring/src/test/resources/project/gradle-kts/gitignore.gen

@@ -0,0 +1,26 @@
+.gradle
+/build/
+!gradle/wrapper/gradle-wrapper.jar
+
+### STS ###
+.apt_generated
+.classpath
+.factorypath
+.project
+.settings
+.springBeans
+.sts4-cache
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+/out/
+
+### NetBeans ###
+/nbproject/private/
+/nbbuild/
+/dist/
+/nbdist/
+/.nb-gradle/

initializr-generator-spring/src/test/resources/project/gradle-kts/kotlin-java11-build.gradle.kts.gen

@@ -0,0 +1,30 @@
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+
+plugins {
+	id("org.springframework.boot") version "2.1.1.RELEASE"
+	id("io.spring.dependency-management") version "1.0.6.RELEASE"
+	kotlin("jvm") version "1.1.1"
+	kotlin("plugin.spring") version "1.1.1"
+}
+
+group = "com.example"
+version = "0.0.1-SNAPSHOT"
+java.sourceCompatibility = JavaVersion.VERSION_11
+
+repositories {
+	mavenCentral()
+}
+
+dependencies {
+	implementation("org.springframework.boot:spring-boot-starter")
+	implementation("org.jetbrains.kotlin:kotlin-reflect")
+	implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8")
+	testImplementation("org.springframework.boot:spring-boot-starter-test")
+}
+
+tasks.withType<KotlinCompile> {
+	kotlinOptions {
+		freeCompilerArgs = listOf("-Xjsr305=strict")
+		jvmTarget = "1.8"
+	}
+}

initializr-generator-spring/src/test/resources/project/gradle-kts/repositories-build.gradle.kts.gen

@@ -0,0 +1,21 @@
+plugins {
+	id("org.springframework.boot") version "2.1.1.RELEASE"
+	id("io.spring.dependency-management") version "1.0.6.RELEASE"
+	java
+}
+
+group = "com.example"
+version = "0.0.1-SNAPSHOT"
+java.sourceCompatibility = JavaVersion.VERSION_1_8
+
+repositories {
+	mavenCentral()
+	maven { url = uri("https://example.com/foo") }
+	maven { url = uri("https://example.com/bar") }
+}
+
+dependencies {
+	implementation("org.acme:bar")
+	implementation("org.acme:foo")
+	testImplementation("org.springframework.boot:spring-boot-starter-test")
+}

initializr-generator-spring/src/test/resources/project/gradle-kts/repositories-milestone-build.gradle.kts.gen

@@ -0,0 +1,20 @@
+plugins {
+	id("org.springframework.boot") version "2.2.0.M1"
+	id("io.spring.dependency-management") version "1.0.6.RELEASE"
+	java
+}
+
+group = "com.example"
+version = "0.0.1-SNAPSHOT"
+java.sourceCompatibility = JavaVersion.VERSION_1_8
+
+repositories {
+	mavenCentral()
+	maven { url = uri("https://repo.spring.io/snapshot") }
+	maven { url = uri("https://repo.spring.io/milestone") }
+}
+
+dependencies {
+	implementation("org.acme:foo")
+	testImplementation("org.springframework.boot:spring-boot-starter-test")
+}

initializr-generator-spring/src/test/resources/project/gradle-kts/version-override-build.gradle.kts.gen

@@ -0,0 +1,21 @@
+plugins {
+	id("org.springframework.boot") version "2.1.1.RELEASE"
+	id("io.spring.dependency-management") version "1.0.6.RELEASE"
+	java
+}
+
+group = "com.example"
+version = "0.0.1-SNAPSHOT"
+java.sourceCompatibility = JavaVersion.VERSION_1_8
+
+repositories {
+	mavenCentral()
+}
+
+extra["springBarVersion"] = "0.2.0.RELEASE"
+extra["spring-foo.version"] = "0.1.0.RELEASE"
+
+dependencies {
+	implementation("org.springframework.boot:spring-boot-starter-web")
+	testImplementation("org.springframework.boot:spring-boot-starter-test")
+}

initializr-generator-spring/src/test/resources/project/groovy/standard/build.gradle.kts.gen

@@ -0,0 +1,19 @@
+plugins {
+	id("org.springframework.boot") version "2.1.1.RELEASE"
+	id("io.spring.dependency-management") version "1.0.6.RELEASE"
+	groovy
+}
+
+group = "com.example"
+version = "0.0.1-SNAPSHOT"
+java.sourceCompatibility = JavaVersion.VERSION_1_8
+
+repositories {
+	mavenCentral()
+}
+
+dependencies {
+	implementation("org.springframework.boot:spring-boot-starter")
+	implementation("org.codehaus.groovy:groovy")
+	testImplementation("org.springframework.boot:spring-boot-starter-test")
+}

initializr-generator-spring/src/test/resources/project/groovy/standard/war-build.gradle.kts.gen

@@ -0,0 +1,21 @@
+plugins {
+	id("org.springframework.boot") version "2.1.1.RELEASE"
+	id("io.spring.dependency-management") version "1.0.6.RELEASE"
+	war
+	groovy
+}
+
+group = "com.example"
+version = "0.0.1-SNAPSHOT"
+java.sourceCompatibility = JavaVersion.VERSION_1_8
+
+repositories {
+	mavenCentral()
+}
+
+dependencies {
+	implementation("org.springframework.boot:spring-boot-starter-web")
+	implementation("org.codehaus.groovy:groovy")
+	providedRuntime("org.springframework.boot:spring-boot-starter-tomcat")
+	testImplementation("org.springframework.boot:spring-boot-starter-test")
+}

initializr-generator-spring/src/test/resources/project/java/standard/build.gradle.kts.gen

@@ -0,0 +1,18 @@
+plugins {
+	id("org.springframework.boot") version "2.1.1.RELEASE"
+	id("io.spring.dependency-management") version "1.0.6.RELEASE"
+	java
+}
+
+group = "com.example"
+version = "0.0.1-SNAPSHOT"
+java.sourceCompatibility = JavaVersion.VERSION_1_8
+
+repositories {
+	mavenCentral()
+}
+
+dependencies {
+	implementation("org.springframework.boot:spring-boot-starter")
+	testImplementation("org.springframework.boot:spring-boot-starter-test")
+}

initializr-generator-spring/src/test/resources/project/java/standard/war-build.gradle.kts.gen

@@ -0,0 +1,20 @@
+plugins {
+	id("org.springframework.boot") version "2.1.1.RELEASE"
+	id("io.spring.dependency-management") version "1.0.6.RELEASE"
+	java
+	war
+}
+
+group = "com.example"
+version = "0.0.1-SNAPSHOT"
+java.sourceCompatibility = JavaVersion.VERSION_1_8
+
+repositories {
+	mavenCentral()
+}
+
+dependencies {
+	implementation("org.springframework.boot:spring-boot-starter-web")
+	providedRuntime("org.springframework.boot:spring-boot-starter-tomcat")
+	testImplementation("org.springframework.boot:spring-boot-starter-test")
+}

initializr-generator-spring/src/test/resources/project/kotlin/standard/build.gradle.kts.gen

@@ -0,0 +1,30 @@
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+
+plugins {
+	id("org.springframework.boot") version "2.1.1.RELEASE"
+	id("io.spring.dependency-management") version "1.0.6.RELEASE"
+	kotlin("jvm") version "1.1.1"
+	kotlin("plugin.spring") version "1.1.1"
+}
+
+group = "com.example"
+version = "0.0.1-SNAPSHOT"
+java.sourceCompatibility = JavaVersion.VERSION_1_8
+
+repositories {
+	mavenCentral()
+}
+
+dependencies {
+	implementation("org.springframework.boot:spring-boot-starter")
+	implementation("org.jetbrains.kotlin:kotlin-reflect")
+	implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8")
+	testImplementation("org.springframework.boot:spring-boot-starter-test")
+}
+
+tasks.withType<KotlinCompile> {
+	kotlinOptions {
+		freeCompilerArgs = listOf("-Xjsr305=strict")
+		jvmTarget = "1.8"
+	}
+}

initializr-generator-spring/src/test/resources/project/kotlin/standard/war-build.gradle.kts.gen

@@ -0,0 +1,32 @@
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+
+plugins {
+	id("org.springframework.boot") version "2.1.1.RELEASE"
+	id("io.spring.dependency-management") version "1.0.6.RELEASE"
+	war
+	kotlin("jvm") version "1.1.1"
+	kotlin("plugin.spring") version "1.1.1"
+}
+
+group = "com.example"
+version = "0.0.1-SNAPSHOT"
+java.sourceCompatibility = JavaVersion.VERSION_1_8
+
+repositories {
+	mavenCentral()
+}
+
+dependencies {
+	implementation("org.springframework.boot:spring-boot-starter-web")
+	implementation("org.jetbrains.kotlin:kotlin-reflect")
+	implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8")
+	providedRuntime("org.springframework.boot:spring-boot-starter-tomcat")
+	testImplementation("org.springframework.boot:spring-boot-starter-test")
+}
+
+tasks.withType<KotlinCompile> {
+	kotlinOptions {
+		freeCompilerArgs = listOf("-Xjsr305=strict")
+		jvmTarget = "1.8"
+	}
+}