Provide default groupId for AOT processing

Framework requires the `groupId` passed to the AOT processing
to be non-empty, so a default should be used if the build
system does not provide a value.

See gh-32696

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/SpringApplicationAotProcessor.java

@@ -27,6 +27,7 @@ import org.springframework.context.aot.ContextAotProcessor;
 import org.springframework.context.support.GenericApplicationContext;
 import org.springframework.util.Assert;
 import org.springframework.util.ReflectionUtils;
+import org.springframework.util.StringUtils;
 import org.springframework.util.function.ThrowingSupplier;
 
 /**
@@ -68,7 +69,8 @@ public class SpringApplicationAotProcessor extends ContextAotProcessor {
 				+ " <applicationName> <sourceOutput> <resourceOutput> <classOutput> <groupId> <artifactId> <originalArgs...>");
 		Class<?> application = Class.forName(args[0]);
 		Settings settings = Settings.builder().sourceOutput(Paths.get(args[1])).resourceOutput(Paths.get(args[2]))
-				.classOutput(Paths.get(args[3])).groupId(args[4]).artifactId(args[5]).build();
+				.classOutput(Paths.get(args[3])).groupId((StringUtils.hasText(args[4])) ? args[4] : "unspecified")
+				.artifactId(args[5]).build();
 		String[] applicationArgs = (args.length > requiredArgs) ? Arrays.copyOfRange(args, requiredArgs, args.length)
 				: new String[0];
 		new SpringApplicationAotProcessor(application, settings, applicationArgs).process();

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/SpringApplicationAotProcessorTests.java

@@ -63,7 +63,7 @@ class SpringApplicationAotProcessorTests {
 	}
 
 	@Test
-	void invokeMainParseArgumentsAndInvokesRunMethod(@TempDir Path directory) throws Exception {
+	void invokeMainParsesArgumentsAndInvokesRunMethod(@TempDir Path directory) throws Exception {
 		String[] mainArguments = new String[] { SampleApplication.class.getName(),
 				directory.resolve("source").toString(), directory.resolve("resource").toString(),
 				directory.resolve("class").toString(), "com.example", "example", "1", "2" };
@@ -72,6 +72,16 @@ class SpringApplicationAotProcessorTests {
 		assertThat(SampleApplication.postRunInvoked).isFalse();
 	}
 
+	@Test
+	void invokeMainParsesArgumentsAndInvokesRunMethodWithoutGroupId(@TempDir Path directory) throws Exception {
+		String[] mainArguments = new String[] { SampleApplication.class.getName(),
+				directory.resolve("source").toString(), directory.resolve("resource").toString(),
+				directory.resolve("class").toString(), "", "example", "1", "2" };
+		SpringApplicationAotProcessor.main(mainArguments);
+		assertThat(SampleApplication.argsHolder).containsExactly("1", "2");
+		assertThat(SampleApplication.postRunInvoked).isFalse();
+	}
+
 	@Test
 	void invokeMainWithMissingArguments() {
 		assertThatIllegalArgumentException()