Move checkstyle config to Gradle convention

This commit moves the checkstyle conventions from the build.gradle
script to a buildSrc convention, ensuring that the same configuration is
applied to all checkstyle tasks.

See gh-30339

build.gradle

@@ -49,7 +49,6 @@ configure([rootProject] + javaProjects) { project ->
 
 	apply plugin: "java"
 	apply plugin: "java-test-fixtures"
-	apply plugin: "checkstyle"
 	apply plugin: 'org.springframework.build.conventions'
 	apply from: "${rootDir}/gradle/toolchains.gradle"
 	apply from: "${rootDir}/gradle/ide.gradle"
@@ -77,18 +76,6 @@ configure([rootProject] + javaProjects) { project ->
 				 "--add-opens=java.base/java.util=ALL-UNNAMED"])
 	}
 
-	checkstyle {
-		toolVersion = "10.9.3"
-		configDirectory.set(rootProject.file("src/checkstyle"))
-	}
-
-	tasks.named("checkstyleMain").configure {
-		maxHeapSize = "1g"
-	}
-
-	tasks.named("checkstyleTest").configure {
-		maxHeapSize = "1g"
-	}
 
 	dependencies {
 		dependencyManagement(enforcedPlatform(dependencies.project(path: ":framework-platform")))
@@ -109,7 +96,6 @@ configure([rootProject] + javaProjects) { project ->
 		// JSR-305 only used for non-required meta-annotations
 		compileOnly("com.google.code.findbugs:jsr305")
 		testCompileOnly("com.google.code.findbugs:jsr305")
-		checkstyle("io.spring.javaformat:spring-javaformat-checkstyle:0.0.38")
 	}
 
 	ext.javadocLinks = [
@@ -168,8 +154,4 @@ configure(rootProject) {
 		}
 	}
 
-	tasks.named("checkstyleNohttp").configure {
-		maxHeapSize = "1g"
-	}
-
 }

buildSrc/build.gradle

@@ -1,5 +1,7 @@
 plugins {
 	id 'java-gradle-plugin'
+	id 'checkstyle'
+	id 'io.spring.javaformat' version "${javaFormatVersion}"
 }
 
 repositories {
@@ -17,10 +19,12 @@ ext {
 }
 
 dependencies {
+	checkstyle "io.spring.javaformat:spring-javaformat-checkstyle:${javaFormatVersion}"
 	implementation("org.jetbrains.kotlin:kotlin-gradle-plugin:${kotlinVersion}")
 	implementation("org.jetbrains.kotlin:kotlin-compiler-embeddable:${kotlinVersion}")
 	implementation "me.champeau.gradle:japicmp-gradle-plugin:0.3.0"
 	implementation "org.gradle:test-retry-gradle-plugin:1.4.1"
+	implementation("io.spring.javaformat:spring-javaformat-gradle-plugin:${javaFormatVersion}")
 }
 
 gradlePlugin {

buildSrc/gradle.properties

@@ -1 +1,2 @@
 org.gradle.caching=true
+javaFormatVersion=0.0.38

buildSrc/src/main/java/org/springframework/build/CheckstyleConventions.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright 2002-2023 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
+ *
+ *      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 org.springframework.build;
+
+import io.spring.javaformat.gradle.SpringJavaFormatPlugin;
+import io.spring.javaformat.gradle.tasks.Format;
+import org.gradle.api.Plugin;
+import org.gradle.api.Project;
+import org.gradle.api.artifacts.DependencySet;
+import org.gradle.api.plugins.JavaBasePlugin;
+import org.gradle.api.plugins.quality.Checkstyle;
+import org.gradle.api.plugins.quality.CheckstyleExtension;
+import org.gradle.api.plugins.quality.CheckstylePlugin;
+
+/**
+ * {@link Plugin} that applies conventions for checkstyle.
+ * @author Brian Clozel
+ */
+public class CheckstyleConventions {
+
+	/**
+	 * Applies the Spring Java Format and Checkstyle plugins with the project conventions.
+	 * @param project the current project
+	 */
+	public void apply(Project project) {
+		project.getPlugins().withType(JavaBasePlugin.class, (java) -> {
+			project.getPlugins().apply(CheckstylePlugin.class);
+			project.getTasks().withType(Checkstyle.class).forEach(checkstyle -> checkstyle.getMaxHeapSize().set("1g"));
+			CheckstyleExtension checkstyle = project.getExtensions().getByType(CheckstyleExtension.class);
+			checkstyle.setToolVersion("10.9.1");
+			checkstyle.getConfigDirectory().set(project.getRootProject().file("src/checkstyle"));
+			String version = SpringJavaFormatPlugin.class.getPackage().getImplementationVersion();
+			DependencySet checkstyleDependencies = project.getConfigurations().getByName("checkstyle").getDependencies();
+			checkstyleDependencies
+				.add(project.getDependencies().create("io.spring.javaformat:spring-javaformat-checkstyle:" + version));
+		});
+	}
+
+}

buildSrc/src/main/java/org/springframework/build/ConventionsPlugin.java

@@ -25,10 +25,8 @@ import org.jetbrains.kotlin.gradle.plugin.KotlinBasePlugin;
  * Plugin to apply conventions to projects that are part of Spring Framework's build.
  * Conventions are applied in response to various plugins being applied.
  *
- * When the {@link JavaBasePlugin} is applied, the conventions in {@link TestConventions}
- * are applied.
- * When the {@link JavaBasePlugin} is applied, the conventions in {@link JavaConventions}
- * are applied.
+ * When the {@link JavaBasePlugin} is applied, the conventions in {@link CheckstyleConventions},
+ * {@link TestConventions} and {@link JavaConventions} are applied.
  * When the {@link KotlinBasePlugin} is applied, the conventions in {@link KotlinConventions}
  * are applied.
  *
@@ -38,6 +36,7 @@ public class ConventionsPlugin implements Plugin<Project> {
 
 	@Override
 	public void apply(Project project) {
+		new CheckstyleConventions().apply(project);
 		new JavaConventions().apply(project);
 		new KotlinConventions().apply(project);
 		new TestConventions().apply(project);