Merge pull request #20179 from dreis2211

* gh-20179:
  Polish "Allow Gradle tasks to be executed with a custom Java home"
  Allow Gradle tasks to be executed with a custom Java home

Closes gh-20179

Author: wilkinsona

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

@@ -26,6 +26,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.TreeMap;
+import java.util.function.Consumer;
 
 import io.spring.javaformat.gradle.FormatTask;
 import io.spring.javaformat.gradle.SpringJavaFormatPlugin;
@@ -127,14 +128,22 @@ private void applyJavaConventions(Project project) {
 			project.setProperty("sourceCompatibility", "1.8");
 			project.getTasks().withType(JavaCompile.class, (compile) -> {
 				compile.getOptions().setEncoding("UTF-8");
+				withOptionalBuildJavaHome(project, (javaHome) -> {
+					compile.getOptions().setFork(true);
+					compile.getOptions().getForkOptions().setJavaHome(new File(javaHome));
+					compile.getOptions().getForkOptions().setExecutable(javaHome + "/bin/javac");
+				});
 				List<String> args = compile.getOptions().getCompilerArgs();
 				if (!args.contains("-parameters")) {
 					args.add("-parameters");
 				}
 			});
-			project.getTasks().withType(Javadoc.class,
-					(javadoc) -> javadoc.getOptions().source("1.8").encoding("UTF-8"));
+			project.getTasks().withType(Javadoc.class, (javadoc) -> {
+				javadoc.getOptions().source("1.8").encoding("UTF-8");
+				withOptionalBuildJavaHome(project, (javaHome) -> javadoc.setExecutable(javaHome + "/bin/javadoc"));
+			});
 			project.getTasks().withType(Test.class, (test) -> {
+				withOptionalBuildJavaHome(project, (javaHome) -> test.setExecutable(javaHome + "/bin/java"));
 				test.useJUnitPlatform();
 				test.setMaxHeapSize("1024M");
 			});
@@ -192,6 +201,13 @@ private File createLegalFile(File source, String filename) {
 		return legalFile;
 	}
 
+	private void withOptionalBuildJavaHome(Project project, Consumer<String> consumer) {
+		String buildJavaHome = (String) project.findProperty("buildJavaHome");
+		if (buildJavaHome != null && !buildJavaHome.isEmpty()) {
+			consumer.accept(buildJavaHome);
+		}
+	}
+
 	private void configureSpringJavaFormat(Project project) {
 		project.getPlugins().apply(SpringJavaFormatPlugin.class);
 		project.getTasks().withType(FormatTask.class, (formatTask) -> formatTask.setEncoding("UTF-8"));

settings.gradle

@@ -28,6 +28,16 @@ plugins {
 
 rootProject.name="spring-boot-build"
 
+settings.gradle.projectsLoaded {
+	gradleEnterprise {
+		buildScan {
+			if (settings.gradle.rootProject.hasProperty('buildJavaHome')) {
+				value('Build Java home', settings.gradle.rootProject.getProperty('buildJavaHome'))
+			}
+		}
+	}
+}
+
 include "spring-boot-project:spring-boot-dependencies"
 include "spring-boot-project:spring-boot-parent"
 include "spring-boot-project:spring-boot-tools:spring-boot-antlib"