Merge branch '3.1.x' into 3.2.x

Closes gh-39268

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/tracing/TracingProperties.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2023 the original author or authors.
+ * Copyright 2012-2024 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -224,7 +224,7 @@ public class TracingProperties {
 		/**
 		 * Supported propagation types. The declared order of the values matter.
 		 */
-		enum PropagationType {
+		public enum PropagationType {
 
 			/**
 			 * <a href="https://www.w3.org/TR/trace-context/">W3C</a> propagation.