diff --git a/core/server/master/src/main/java/alluxio/master/file/DefaultFileSystemMaster.java b/core/server/master/src/main/java/alluxio/master/file/DefaultFileSystemMaster.java
index <HASH>..<HASH> 100644
--- a/core/server/master/src/main/java/alluxio/master/file/DefaultFileSystemMaster.java
+++ b/core/server/master/src/main/java/alluxio/master/file/DefaultFileSystemMaster.java
@@ -153,6 +153,7 @@ import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Future;
 import java.util.concurrent.LinkedBlockingQueue;
 
+import javax.annotation.Nullable;
 import javax.annotation.concurrent.NotThreadSafe;
 
 /**
@@ -1397,6 +1398,7 @@ public final class DefaultFileSystemMaster extends AbstractMaster implements Fil
      * @param alluxioUri Alluxio path to delete
      * @return true, if path can be deleted recursively from UFS; false, otherwise
      */
+    @Nullable
     private boolean isRecursiveDeleteSafe(AlluxioURI alluxioUri) {
       if (alluxioUri == null || !alluxioUri.toString().startsWith(mRootPath.toString())) {
         // Path is not part of sub-tree being deleted
add the @Nullable annotation for method for method parameters which are allowed to be null