Polishing

spring-context/src/main/java/org/springframework/context/annotation/ConfigurationClassPostProcessor.java

@@ -319,6 +319,7 @@ public class ConfigurationClassPostProcessor implements BeanDefinitionRegistryPo
 	}
 
 	@Override
+	@Nullable
 	public BeanFactoryInitializationAotContribution processAheadOfTime(ConfigurableListableBeanFactory beanFactory) {
 		boolean hasPropertySourceDescriptors = !CollectionUtils.isEmpty(this.propertySourceDescriptors);
 		boolean hasImportRegistry = beanFactory.containsBean(IMPORT_REGISTRY_BEAN_NAME);