Merge branch '3.3.x'

Closes gh-41919

Author: snicoll

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/source/SpringConfigurationPropertySource.java

@@ -180,7 +180,7 @@ private static boolean isFullEnumerable(PropertySource<?> source) {
 	}
 
 	private static PropertySource<?> getRootSource(PropertySource<?> source) {
-		while (source.getSource() != null && source.getSource() instanceof PropertySource<?> propertySource) {
+		while (source.getSource() instanceof PropertySource<?> propertySource) {
 			source = propertySource;
 		}
 		return source;