Avoid using temp before @TempDir has initialized it

Closes gh-28748

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

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.build;
 
+import java.io.File;
 import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
@@ -23,16 +24,21 @@ import java.util.Map;
 import java.util.Set;
 import java.util.TreeMap;
 import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import io.spring.javaformat.gradle.SpringJavaFormatPlugin;
 import io.spring.javaformat.gradle.tasks.CheckFormat;
 import io.spring.javaformat.gradle.tasks.Format;
+import org.gradle.api.Action;
+import org.gradle.api.GradleException;
 import org.gradle.api.JavaVersion;
 import org.gradle.api.Project;
+import org.gradle.api.Task;
 import org.gradle.api.artifacts.Configuration;
 import org.gradle.api.artifacts.ConfigurationContainer;
 import org.gradle.api.artifacts.Dependency;
 import org.gradle.api.artifacts.DependencySet;
+import org.gradle.api.file.FileTree;
 import org.gradle.api.plugins.JavaBasePlugin;
 import org.gradle.api.plugins.JavaPlugin;
 import org.gradle.api.plugins.JavaPluginExtension;
@@ -178,7 +184,10 @@ class JavaConventions {
 	}
 
 	private void configureJavadocConventions(Project project) {
-		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");
+			javadoc.doFirst(new VerifyPackageInfo());
+		});
 	}
 
 	private void configureJavaConventions(Project project) {
@@ -264,4 +273,22 @@ class JavaConventions {
 		project.getTasks().getByName(JavaBasePlugin.CHECK_TASK_NAME).dependsOn(checkClasspathForProhibitedDependencies);
 	}
 
+	private static final class VerifyPackageInfo implements Action<Task> {
+
+		@Override
+		public void execute(Task javadoc) {
+			FileTree source = ((Javadoc) javadoc).getSource();
+			Stream<File> dirs = source.getFiles().stream().map((file) -> file.getParentFile()).distinct();
+			Set<File> missingPackageInfo = dirs.map((file) -> new File(file, "package-info.java"))
+					.filter((packageInfo) -> !packageInfo.isFile()).collect(Collectors.toSet());
+			if (!missingPackageInfo.isEmpty()) {
+				StringBuilder message = new StringBuilder(
+						"A package-info.java file was missing from the following directories:\n");
+				missingPackageInfo.forEach((packageInfo) -> message.append("\t" + packageInfo.getParentFile() + "\n"));
+				throw new GradleException(message.toString());
+			}
+		}
+
+	}
+
 }

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/java/org/springframework/boot/gradle/tasks/bundling/BootBuildImageTests.java

@@ -24,6 +24,7 @@ import java.util.Map;
 import org.gradle.api.GradleException;
 import org.gradle.api.JavaVersion;
 import org.gradle.api.Project;
+import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
 
@@ -45,15 +46,13 @@ import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
  */
 class BootBuildImageTests {
 
-	@TempDir
-	File temp;
-
 	Project project;
 
-	private final BootBuildImage buildImage;
+	private BootBuildImage buildImage;
 
-	BootBuildImageTests() {
-		File projectDir = new File(this.temp, "project");
+	@BeforeEach
+	void setUp(@TempDir File temp) {
+		File projectDir = new File(temp, "project");
 		projectDir.mkdirs();
 		this.project = GradleProjectBuilder.builder().withProjectDir(projectDir).withName("build-image-test").build();
 		this.project.setDescription("Test project for BootBuildImage");