Consistently set target type in generated code

Previously, a bean definition that is optimized AOT could have
different metadata based on whether its resolved type had a generic or
not. This is due to RootBeanDefinition taking either a Class or a
ResolvableType doing fundamentally different things. While the former
sets the bean class which is to little use with an instance supplier,
the latter specifies the target type of the bean.

This commit sets the target type of the bean, using the existing
setter methods that take either a class or a ResolvableType and set the
same attribute consistently.

Closes gh-30689

spring-context/src/test/java/org/springframework/context/aot/ApplicationContextAotGeneratorTests.java

@@ -45,8 +45,13 @@ import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
 import org.springframework.beans.factory.config.BeanPostProcessor;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
 import org.springframework.beans.factory.support.BeanDefinitionBuilder;
+import org.springframework.beans.factory.support.DefaultListableBeanFactory;
 import org.springframework.beans.factory.support.RegisteredBean;
 import org.springframework.beans.factory.support.RootBeanDefinition;
+import org.springframework.beans.testfixture.beans.factory.aot.TestHierarchy;
+import org.springframework.beans.testfixture.beans.factory.aot.TestHierarchy.Implementation;
+import org.springframework.beans.testfixture.beans.factory.aot.TestHierarchy.One;
+import org.springframework.beans.testfixture.beans.factory.aot.TestHierarchy.Two;
 import org.springframework.context.ApplicationContextInitializer;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.AnnotationConfigUtils;
@@ -75,6 +80,7 @@ import org.springframework.core.test.tools.CompileWithForkedClassLoader;
 import org.springframework.core.test.tools.Compiled;
 import org.springframework.core.test.tools.TestCompiler;
 import org.springframework.mock.env.MockEnvironment;
+import org.springframework.util.ReflectionUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -327,6 +333,22 @@ class ApplicationContextAotGeneratorTests {
 		});
 	}
 
+	@Test // gh-30689
+	void processAheadOfTimeWithExplicitResolvableType() {
+		GenericApplicationContext applicationContext = new GenericApplicationContext();
+		DefaultListableBeanFactory beanFactory = applicationContext.getDefaultListableBeanFactory();
+		RootBeanDefinition beanDefinition = new RootBeanDefinition(One.class);
+		beanDefinition.setResolvedFactoryMethod(ReflectionUtils.findMethod(TestHierarchy.class, "oneBean"));
+		// Override target type
+		beanDefinition.setTargetType(Two.class);
+		beanFactory.registerBeanDefinition("hierarchyBean", beanDefinition);
+		testCompiledResult(applicationContext, (initializer, compiled) -> {
+			GenericApplicationContext freshApplicationContext = toFreshApplicationContext(initializer);
+			assertThat(freshApplicationContext.getBean(Two.class))
+					.isInstanceOf(Implementation.class);
+		});
+	}
+
 	@Nested
 	@CompileWithForkedClassLoader
 	class ConfigurationClassCglibProxy {