diff --git a/config/src/main/java/org/springframework/security/config/annotation/authentication/configuration/InitializeUserDetailsBeanManagerConfigurer.java b/config/src/main/java/org/springframework/security/config/annotation/authentication/configuration/InitializeUserDetailsBeanManagerConfigurer.java
index 7266fbfa777..98af4d70db4 100644
--- a/config/src/main/java/org/springframework/security/config/annotation/authentication/configuration/InitializeUserDetailsBeanManagerConfigurer.java
+++ b/config/src/main/java/org/springframework/security/config/annotation/authentication/configuration/InitializeUserDetailsBeanManagerConfigurer.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -82,7 +82,7 @@ public void configure(AuthenticationManagerBuilder auth) throws Exception {
 		}
 
 		/**
-		 * @return
+		 * @return a bean of the requested class if there's just a single registered component, null otherwise.
 		 */
 		private <T> T getBeanOrNull(Class<T> type) {
 			String[] userDetailsBeanNames = InitializeUserDetailsBeanManagerConfigurer.this.context