Skip processAot and processTestAot if there is no main or test code

Closes gh-32424

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

@@ -21,6 +21,7 @@ import java.io.IOException;
 import java.nio.file.Files;
 import java.util.List;
 
+import org.gradle.testkit.runner.TaskOutcome;
 import org.junit.jupiter.api.TestTemplate;
 
 import org.springframework.boot.gradle.junit.GradleCompatibility;
@@ -94,4 +95,16 @@ class SpringBootAotPluginIntegrationTests {
 		assertThat(output).contains("org.jboss.logging" + File.separatorChar + "jboss-logging");
 	}
 
+	@TestTemplate
+	void processAotIsSkippedWhenProjectHasNoMainSource() {
+		assertThat(this.gradleBuild.build("processAot").task(":processAot").getOutcome())
+				.isEqualTo(TaskOutcome.NO_SOURCE);
+	}
+
+	@TestTemplate
+	void processTestAotIsSkippedWhenProjectHasNoTestSource() {
+		assertThat(this.gradleBuild.build("processTestAot").task(":processTestAot").getOutcome())
+				.isEqualTo(TaskOutcome.NO_SOURCE);
+	}
+
 }

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/resources/org/springframework/boot/gradle/plugin/SpringBootAotPluginIntegrationTests-processAotIsSkippedWhenProjectHasNoMainSource.gradle

@@ -0,0 +1,13 @@
+plugins {
+	id 'org.springframework.boot'
+	id 'org.springframework.boot.aot'
+	id 'java'
+}
+
+repositories {
+	mavenCentral()
+}
+
+springBoot {
+	mainClass = 'com.example.Application'
+}

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/test/resources/org/springframework/boot/gradle/plugin/SpringBootAotPluginIntegrationTests-processTestAotIsSkippedWhenProjectHasNoTestSource.gradle

@@ -0,0 +1,13 @@
+plugins {
+	id 'org.springframework.boot'
+	id 'org.springframework.boot.aot'
+	id 'java'
+}
+
+repositories {
+	mavenCentral()
+}
+
+springBoot {
+	mainClass = 'com.example.Application'
+}