Merge pull request #12641 from Rui Figueira

* gh-12641:
  Polish “Configure Kotlin compiler to use -java-parameters by default”
  Configure Kotlin compiler to use -java-parameters by default

spring-boot-project/spring-boot-docs/src/main/asciidoc/production-ready-features.adoc

@@ -532,10 +532,11 @@ JSON request body. When exposed via JMX, the parameters are mapped to the parame
 the MBean's operations. Parameters are required by default. They can be made optional
 by annotating them with `@org.springframework.lang.Nullable`.
 
-NOTE: To allow the input to be mapped to the operation method's parameters, code
-implementing an endpoint should be compiled with `-parameters`. This will happen
-automatically if you are using Spring Boot's Gradle plugin or if you are using Maven
-and `spring-boot-starter-parent`.
+NOTE: To allow the input to be mapped to the operation method's parameters, Java code
+implementing an endpoint should be compiled with `-parameters`, and Kotlin code
+implementing an endpoint should be compiled with `-java-parameters`. This will happen
+automatically if you are using Spring Boot's Gradle plugin or if you are using Maven and
+`spring-boot-starter-parent`.
 
 
 

spring-boot-project/spring-boot-parent/pom.xml

@@ -294,6 +294,7 @@
 						<jvmTarget>${java.version}</jvmTarget>
 						<apiVersion>1.1</apiVersion>
 						<languageVersion>1.1</languageVersion>
+						<javaParameters>true</javaParameters>
 					</configuration>
 				</plugin>
 				<plugin>

spring-boot-project/spring-boot-starters/spring-boot-starter-parent/pom.xml

@@ -51,6 +51,7 @@
 					<version>${kotlin.version}</version>
 					<configuration>
 						<jvmTarget>${java.version}</jvmTarget>
+						<javaParameters>true</javaParameters>
 					</configuration>
 					<executions>
 						<execution>

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/asciidoc/reacting.adoc

@@ -36,6 +36,7 @@ plugin:
 1. Aligns the Kotlin version used in Spring Boot's dependency management with the version
    of the plugin. This is achieved by setting the `kotlin.version` property with a value
    that matches the version of the Kotlin plugin.
+2. Configures any `KotlinCompile` tasks to use the `-java-parameters` compiler argument.
 
 
 

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/plugin/KotlinPluginAction.java

@@ -20,6 +20,7 @@ import org.gradle.api.Plugin;
 import org.gradle.api.Project;
 import org.gradle.api.plugins.ExtraPropertiesExtension;
 import org.jetbrains.kotlin.gradle.plugin.KotlinPluginWrapper;
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile;
 
 /**
  * {@link PluginApplicationAction} that reacts to Kotlin's Gradle plugin being applied by
@@ -39,6 +40,12 @@ class KotlinPluginAction implements PluginApplicationAction {
 		if (!extraProperties.has("kotlin.version")) {
 			extraProperties.set("kotlin.version", kotlinVersion);
 		}
+		enableJavaParametersOption(project);
+	}
+
+	private void enableJavaParametersOption(Project project) {
+		project.getTasks().withType(KotlinCompile.class,
+				(compile) -> compile.getKotlinOptions().setJavaParameters(true));
 	}
 
 	@Override

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/plugin/KotlinPluginActionIntegrationTests.java

@@ -52,4 +52,18 @@ public class KotlinPluginActionIntegrationTests {
 				.containsPattern("org.jetbrains.kotlin:kotlin-stdlib-jdk8:* -> 1.2.10");
 	}
 
+	@Test
+	public void kotlinCompileTasksUseJavaParametersFlagByDefault() {
+		assertThat(this.gradleBuild.build("kotlinCompileTasksJavaParameters").getOutput())
+				.contains("compileKotlin java parameters: true")
+				.contains("compileTestKotlin java parameters: true");
+	}
+
+	@Test
+	public void kotlinCompileTasksCanOverrideDefaultJavaParametersFlag() {
+		assertThat(this.gradleBuild.build("kotlinCompileTasksJavaParameters").getOutput())
+				.contains("compileKotlin java parameters: false")
+				.contains("compileTestKotlin java parameters: false");
+	}
+
 }

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/resources/org/springframework/boot/gradle/plugin/KotlinPluginActionIntegrationTests-kotlinCompileTasksCanOverrideDefaultJavaParametersFlag.gradle

@@ -0,0 +1,25 @@
+buildscript {
+	dependencies {
+		classpath files(pluginClasspath.split(','))
+	}
+}
+
+plugins {
+	id 'org.jetbrains.kotlin.jvm' version '1.2.10'
+}
+
+apply plugin: 'org.springframework.boot'
+
+import org.jetbrains.kotlin.gradle.dsl.KotlinCompile
+
+tasks.withType(KotlinCompile) {
+	kotlinOptions.javaParameters = false
+}
+
+task('kotlinCompileTasksJavaParameters') {
+	doFirst {
+		tasks.withType(KotlinCompile) {
+			println "$name java parameters: ${kotlinOptions.javaParameters}"
+		}
+	}
+}

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/resources/org/springframework/boot/gradle/plugin/KotlinPluginActionIntegrationTests-kotlinCompileTasksUseJavaParametersFlagByDefault.gradle

@@ -0,0 +1,21 @@
+buildscript {
+	dependencies {
+		classpath files(pluginClasspath.split(','))
+	}
+}
+
+plugins {
+	id 'org.jetbrains.kotlin.jvm' version '1.2.10'
+}
+
+apply plugin: 'org.springframework.boot'
+
+import org.jetbrains.kotlin.gradle.dsl.KotlinCompile
+
+task('kotlinCompileTasksJavaParameters') {
+	doFirst {
+		tasks.withType(KotlinCompile) {
+			println "$name java parameters: ${kotlinOptions.javaParameters}"
+		}
+	}
+}