Ensure all files end with a newline

Update all files to ensure that they always end with a new line.

Issue: SPR-16968

spring-messaging/src/main/java/org/springframework/messaging/simp/annotation/support/SendToMethodReturnValueHandler.java

@@ -296,4 +296,4 @@ public class SendToMethodReturnValueHandler implements HandlerMethodReturnValueH
 			return placeholderHelper.replacePlaceholders(destination, this.placeholderResolver);
 		}
 	}
-}
+}