diff --git a/spring-boot/src/main/java/org/springframework/boot/env/SpringApplicationJsonEnvironmentPostProcessor.java b/spring-boot/src/main/java/org/springframework/boot/env/SpringApplicationJsonEnvironmentPostProcessor.java
index 384b99b64e6..0042d5c87be 100644
--- a/spring-boot/src/main/java/org/springframework/boot/env/SpringApplicationJsonEnvironmentPostProcessor.java
+++ b/spring-boot/src/main/java/org/springframework/boot/env/SpringApplicationJsonEnvironmentPostProcessor.java
@@ -96,6 +96,8 @@ public class SpringApplicationJsonEnvironmentPostProcessor
 
 	/**
 	 * Flatten the map keys using period separator.
+	 * @param map The map that should be flattened
+	 * @return the flattened map
 	 */
 	private Map<String, Object> flatten(Map<String, Object> map) {
 		Map<String, Object> result = new LinkedHashMap<String, Object>();