Configure Kotlin compiler to use -java-parameters by default

See gh-12641

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

@@ -24,7 +24,7 @@ plugin:
    the `bootJar` task.
 6. Configures any `JavaCompile` tasks with no configured encoding to use `UTF-8`.
 7. Configures any `JavaCompile` tasks to use the `-parameters` compiler argument.
-
+8. Configures any `KotlinCompile` tasks to use the `-java-parameters` compiler argument.
 
 
 [[reacting-to-other-plugins-kotlin]]

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 +40,13 @@ 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 +52,17 @@ 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}"
+		}
+	}
+}