Use target of the FactoryBean only if the FactoryBean is public

This commit polishes 85d4a79 so that the target type of factory bean
is only considered if the FactoryBean is accessible. If the FactoryBean
requires protected access, we still generate the code in the package of
the FactoryBean.

Those two commits combined are actually providing a fix for the use
case described in gh-28809.

Closes gh-28809

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

@@ -21,6 +21,7 @@ import java.lang.reflect.Executable;
 import java.util.List;
 import java.util.function.Predicate;
 
+import org.springframework.aot.generate.AccessVisibility;
 import org.springframework.aot.generate.GenerationContext;
 import org.springframework.aot.generate.MethodReference;
 import org.springframework.beans.factory.FactoryBean;
@@ -80,7 +81,9 @@ class DefaultBeanRegistrationCodeFragments extends BeanRegistrationCodeFragments
 
 	private Class<?> extractDeclaringClass(Executable executable) {
 		Class<?> declaringClass = ClassUtils.getUserClass(executable.getDeclaringClass());
-		if (executable instanceof Constructor<?> && FactoryBean.class.isAssignableFrom(declaringClass)) {
+		if (executable instanceof Constructor<?>
+				&& AccessVisibility.forMember(executable) == AccessVisibility.PUBLIC
+				&& FactoryBean.class.isAssignableFrom(declaringClass)) {
 			return ResolvableType.forType(declaringClass).as(FactoryBean.class).getGeneric(0).toClass();
 		}
 		return executable.getDeclaringClass();

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

@@ -51,12 +51,19 @@ class DefaultBeanRegistrationCodeFragmentsTests {
 	}
 
 	@Test
-	void getTargetOnConstructorToFactoryBean() {
+	void getTargetOnConstructorToPublicFactoryBean() {
 		RegisteredBean registeredBean = registerTestBean(TestBean.class);
 		assertThat(createInstance(registeredBean).getTarget(registeredBean,
 				TestBeanFactoryBean.class.getDeclaredConstructors()[0])).isEqualTo(TestBean.class);
 	}
 
+	@Test
+	void getTargetOnConstructorToProtectedFactoryBean() {
+		RegisteredBean registeredBean = registerTestBean(TestBean.class);
+		assertThat(createInstance(registeredBean).getTarget(registeredBean,
+				PrivilegedTestBeanFactoryBean.class.getDeclaredConstructors()[0])).isEqualTo(PrivilegedTestBeanFactoryBean.class);
+	}
+
 	@Test
 	void getTargetOnMethod() {
 		RegisteredBean registeredBean = registerTestBean(TestBean.class);
@@ -135,13 +142,7 @@ class DefaultBeanRegistrationCodeFragmentsTests {
 		return "Test";
 	}
 
-	@SuppressWarnings("unused")
-	static class TestBean {
-
-	}
-
-
-	static class TestBeanFactoryBean implements FactoryBean<TestBean> {
+	static class PrivilegedTestBeanFactoryBean implements FactoryBean<TestBean> {
 
 		@Override
 		public TestBean getObject() throws Exception {

spring-beans/src/testFixtures/java/org/springframework/beans/factory/aot/TestBean.java

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2002-2022 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.beans.factory.aot;
+
+/**
+ * An empty test bean used by code generation.
+ *
+ * @author Stephane Nicoll
+ */
+public class TestBean {
+}

spring-beans/src/testFixtures/java/org/springframework/beans/factory/aot/TestBeanFactoryBean.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2002-2022 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.beans.factory.aot;
+
+import org.springframework.beans.factory.FactoryBean;
+
+/**
+ * A public {@link FactoryBean}.
+ *
+ * @author Stephane Nicoll
+ */
+public class TestBeanFactoryBean implements FactoryBean<TestBean> {
+
+	@Override
+	public TestBean getObject() throws Exception {
+		return new TestBean();
+	}
+
+	@Override
+	public Class<?> getObjectType() {
+		return TestBean.class;
+	}
+
+}