Avoid generated code in the javax package

This commit updates the existing logic to also exclude code generation
in the javax package.

Closes gh-29123

spring-beans/src/main/java/org/springframework/beans/factory/aot/BeanDefinitionMethodGenerator.java

@@ -96,7 +96,7 @@ class BeanDefinitionMethodGenerator {
 		BeanRegistrationCodeFragments codeFragments = getCodeFragments(generationContext,
 				beanRegistrationsCode);
 		ClassName target = codeFragments.getTarget(this.registeredBean, this.constructorOrFactoryMethod);
-		if (!target.canonicalName().startsWith("java.")) {
+		if (isWritablePackageName(target)) {
 			GeneratedClass generatedClass = lookupGeneratedClass(generationContext, target);
 			GeneratedMethods generatedMethods = generatedClass.getMethods().withPrefix(getName());
 			GeneratedMethod generatedMethod = generateBeanDefinitionMethod(generationContext,
@@ -109,6 +109,16 @@ class BeanDefinitionMethodGenerator {
 		return generatedMethod.toMethodReference();
 	}
 
+	/**
+	 * Specify if the {@link ClassName} belongs to a writable package.
+	 * @param target the target to check
+	 * @return {@code true} if generated code in that package is allowed
+	 */
+	private boolean isWritablePackageName(ClassName target) {
+		String packageName = target.packageName();
+		return (!packageName.startsWith("java.") && !packageName.startsWith("javax."));
+	}
+
 	/**
 	 * Return the {@link GeneratedClass} to use for the specified {@code target}.
 	 * <p>If the target class is an inner class, a corresponding inner class in

spring-beans/src/test/java/org/springframework/beans/factory/aot/BeanDefinitionMethodGeneratorTests.java

@@ -24,6 +24,7 @@ import java.util.function.Predicate;
 import java.util.function.Supplier;
 
 import javax.lang.model.element.Modifier;
+import javax.xml.parsers.DocumentBuilderFactory;
 
 import org.junit.jupiter.api.Test;
 
@@ -455,6 +456,37 @@ class BeanDefinitionMethodGeneratorTests {
 		});
 	}
 
+	@Test
+	void generateBeanDefinitionMethodWhenBeanIsInJavaPackage() {
+		RootBeanDefinition beanDefinition = (RootBeanDefinition) BeanDefinitionBuilder
+				.rootBeanDefinition(String.class).addConstructorArgValue("test").getBeanDefinition();
+		testBeanDefinitionMethodInCurrentFile(String.class, beanDefinition);
+	}
+
+	@Test
+	void generateBeanDefinitionMethodWhenBeanIsInJavaxPackage() {
+		RootBeanDefinition beanDefinition = (RootBeanDefinition) BeanDefinitionBuilder
+				.rootBeanDefinition(DocumentBuilderFactory.class).setFactoryMethod("newDefaultInstance").getBeanDefinition();
+		testBeanDefinitionMethodInCurrentFile(DocumentBuilderFactory.class, beanDefinition);
+	}
+
+	private void testBeanDefinitionMethodInCurrentFile(Class<?> targetType, RootBeanDefinition beanDefinition) {
+		RegisteredBean registeredBean = registerBean(new RootBeanDefinition(beanDefinition));
+		BeanDefinitionMethodGenerator generator = new BeanDefinitionMethodGenerator(
+				this.methodGeneratorFactory, registeredBean, null,
+				Collections.emptyList());
+		MethodReference method = generator.generateBeanDefinitionMethod(
+				this.generationContext, this.beanRegistrationsCode);
+		compile(method, (actual, compiled) -> {
+			DefaultListableBeanFactory freshBeanFactory = new DefaultListableBeanFactory();
+			freshBeanFactory.registerBeanDefinition("test", actual);
+			Object bean = freshBeanFactory.getBean("test");
+			assertThat(bean).isInstanceOf(targetType);
+			assertThat(compiled.getSourceFiles().stream().filter(sourceFile ->
+					sourceFile.getClassName().startsWith(targetType.getPackageName()))).isEmpty();
+		});
+	}
+
 	private RegisteredBean registerBean(RootBeanDefinition beanDefinition) {
 		String beanName = "testBean";
 		this.beanFactory.registerBeanDefinition(beanName, beanDefinition);