diff --git a/wise-webapp/src/main/java/com/wisemapping/dao/LabelManager.java b/wise-webapp/src/main/java/com/wisemapping/dao/LabelManager.java
index b6941d7b..017c7da1 100644
--- a/wise-webapp/src/main/java/com/wisemapping/dao/LabelManager.java
+++ b/wise-webapp/src/main/java/com/wisemapping/dao/LabelManager.java
@@ -1,10 +1,14 @@
 package com.wisemapping.dao;
 
 import com.wisemapping.model.Label;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.List;
 
 public interface LabelManager {
 
-    void addLabel(Label label);
+    void addLabel(@NotNull final Label label);
+
+    void saveLabel(@NotNull final Label label);
 
-    void saveLabel(Label label);
 }
diff --git a/wise-webapp/src/main/java/com/wisemapping/dao/LabelManagerImpl.java b/wise-webapp/src/main/java/com/wisemapping/dao/LabelManagerImpl.java
index 657d9423..a075424a 100644
--- a/wise-webapp/src/main/java/com/wisemapping/dao/LabelManagerImpl.java
+++ b/wise-webapp/src/main/java/com/wisemapping/dao/LabelManagerImpl.java
@@ -8,12 +8,12 @@ public class LabelManagerImpl extends HibernateDaoSupport
         implements LabelManager {
 
     @Override
-    public void addLabel(Label label) {
+    public void addLabel(@NotNull final Label label) {
         saveLabel(label);
     }
 
     @Override
-    public void saveLabel(@NotNull Label label) {
+    public void saveLabel(@NotNull final Label label) {
         getSession().save(label);
     }
 }