diff --git a/spring-boot/src/main/java/org/springframework/boot/context/embedded/undertow/UndertowEmbeddedServletContainerFactory.java b/spring-boot/src/main/java/org/springframework/boot/context/embedded/undertow/UndertowEmbeddedServletContainerFactory.java
index 2a9588f8b3..eb8edc0e98 100644
--- a/spring-boot/src/main/java/org/springframework/boot/context/embedded/undertow/UndertowEmbeddedServletContainerFactory.java
+++ b/spring-boot/src/main/java/org/springframework/boot/context/embedded/undertow/UndertowEmbeddedServletContainerFactory.java
@@ -441,6 +441,7 @@ public class UndertowEmbeddedServletContainerFactory
 	 * Return the document root in canonical form. Undertow uses File#getCanonicalFile()
 	 * to determine whether a resource has been requested using the proper case but on
 	 * Windows {@code java.io.tmpdir} may be set as a tilde-compressed pathname.
+	 * @return the canonical document root
 	 */
 	private File getCanonicalDocumentRoot() {
 		try {