Don't consider singleton instances when deducing bean class

Update `RegisteredBean` bean class detection to not consider
singletons. Prior to this commit, any beans that had been instantiated
could return the wrong class, especially if they were implemented using
a lambda.

See gh-28414

spring-beans/src/main/java/org/springframework/beans/factory/support/RegisteredBean.java

@@ -158,9 +158,6 @@ public final class RegisteredBean {
 	 * @return the bean class
 	 */
 	public Class<?> getBeanClass() {
-		if (this.beanFactory.containsSingleton(getBeanName())) {
-			return this.beanFactory.getSingleton(getBeanName()).getClass();
-		}
 		return ClassUtils.getUserClass(getBeanType().toClass());
 	}
 
@@ -169,10 +166,6 @@ public final class RegisteredBean {
 	 * @return the bean type
 	 */
 	public ResolvableType getBeanType() {
-		if (this.beanFactory.containsSingleton(getBeanName())) {
-			return ResolvableType
-					.forInstance(this.beanFactory.getSingleton(getBeanName()));
-		}
 		return getMergedBeanDefinition().getResolvableType();
 	}
 

spring-beans/src/test/java/org/springframework/beans/factory/support/RegisteredBeanTests.java

@@ -21,6 +21,7 @@ import org.junit.jupiter.api.Test;
 
 import org.springframework.beans.factory.NoSuchBeanDefinitionException;
 import org.springframework.beans.factory.config.BeanDefinitionHolder;
+import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
@@ -112,12 +113,6 @@ class RegisteredBeanTests {
 		assertThat(registeredBean.getBeanClass()).isEqualTo(TestBean.class);
 	}
 
-	@Test
-	void getBeanClassWhenSingletonReturnsBeanClass() {
-		RegisteredBean registeredBean = RegisteredBean.of(this.beanFactory, "sb");
-		assertThat(registeredBean.getBeanClass()).isEqualTo(TestBean.class);
-	}
-
 	@Test
 	void getBeanTypeReturnsBeanType() {
 		RegisteredBean registeredBean = RegisteredBean.of(this.beanFactory, "bd");
@@ -125,9 +120,16 @@ class RegisteredBeanTests {
 	}
 
 	@Test
-	void getBeanTypeWhenSingletonReturnsBeanType() {
-		RegisteredBean registeredBean = RegisteredBean.of(this.beanFactory, "sb");
-		assertThat(registeredBean.getBeanType().toClass()).isEqualTo(TestBean.class);
+	void getBeanTypeWhenHasInstanceBackedByLambdaDoesNotReturnLambdaType() {
+		this.beanFactory.registerBeanDefinition("bfpp", new RootBeanDefinition(
+				BeanFactoryPostProcessor.class, RegisteredBeanTests::getBeanFactoryPostProcessorLambda));
+		this.beanFactory.getBean("bfpp");
+		RegisteredBean registeredBean = RegisteredBean.of(this.beanFactory, "bfpp");
+		assertThat(registeredBean.getBeanType().toClass()).isEqualTo(BeanFactoryPostProcessor.class);
+	}
+
+	static BeanFactoryPostProcessor getBeanFactoryPostProcessorLambda() {
+		return bf -> {};
 	}
 
 	@Test