Avoid NPE on BeanDescriptor access with SimpleBeanInfoFactory

Closes gh-29681

(cherry picked from commit d741914)

Author: jhoeller

spring-beans/src/main/java/org/springframework/beans/SimpleBeanInfoFactory.java

@@ -16,6 +16,7 @@
 
 package org.springframework.beans;
 
+import java.beans.BeanDescriptor;
 import java.beans.BeanInfo;
 import java.beans.IntrospectionException;
 import java.beans.PropertyDescriptor;
@@ -51,6 +52,10 @@ public BeanInfo getBeanInfo(Class<?> beanClass) throws IntrospectionException {
 				PropertyDescriptorUtils.determineBasicProperties(beanClass);
 
 		return new SimpleBeanInfo() {
+			@Override
+			public BeanDescriptor getBeanDescriptor() {
+				return new BeanDescriptor(beanClass);
+			}
 			@Override
 			public PropertyDescriptor[] getPropertyDescriptors() {
 				return pds.toArray(PropertyDescriptorUtils.EMPTY_PROPERTY_DESCRIPTOR_ARRAY);

spring-beans/src/test/java/org/springframework/beans/BeanWrapperTests.java

@@ -77,6 +77,21 @@ void aliasedSetterThroughDefaultMethod() {
 		assertThat(accessor.getPropertyValue("aliasedName")).isEqualTo("tom");
 	}
 
+	@Test
+	void replaceWrappedInstance() {
+		GetterBean target = new GetterBean();
+		BeanWrapperImpl accessor = createAccessor(target);
+		accessor.setPropertyValue("name", "tom");
+		assertThat(target.getAliasedName()).isEqualTo("tom");
+		assertThat(accessor.getPropertyValue("aliasedName")).isEqualTo("tom");
+
+		target = new GetterBean();
+		accessor.setWrappedInstance(target);
+		accessor.setPropertyValue("name", "tom");
+		assertThat(target.getAliasedName()).isEqualTo("tom");
+		assertThat(accessor.getPropertyValue("aliasedName")).isEqualTo("tom");
+	}
+
 	@Test
 	void setValidAndInvalidPropertyValuesShouldContainExceptionDetails() {
 		TestBean target = new TestBean();