diff --git a/src/main/java/org/gcube/portlets/user/shareupdates/server/ShareUpdateServiceImpl.java b/src/main/java/org/gcube/portlets/user/shareupdates/server/ShareUpdateServiceImpl.java
index dcc5ac8..51b4fb2 100644
--- a/src/main/java/org/gcube/portlets/user/shareupdates/server/ShareUpdateServiceImpl.java
+++ b/src/main/java/org/gcube/portlets/user/shareupdates/server/ShareUpdateServiceImpl.java
@@ -144,7 +144,7 @@ public class ShareUpdateServiceImpl extends RemoteServiceServlet implements	Shar
 		}
 		*/
 		
-		ArrayList<ItemBean> mentionedUsers = null;
+		ArrayList<ItemBean> mentionedUsers = new ArrayList<>();
 		if (mentionedItems != null && ! mentionedItems.isEmpty()) {
 			mentionedUsers = getMentionsBean(mentionedItems);
 		}
@@ -266,7 +266,7 @@ public class ShareUpdateServiceImpl extends RemoteServiceServlet implements	Shar
 		}
 		*/
 		
-		ArrayList<ItemBean> mentionedUsers = null;
+		ArrayList<ItemBean> mentionedUsers = new ArrayList<>();;
 		if (mentionedItems != null && ! mentionedItems.isEmpty()) {
 			mentionedUsers = getMentionsBean(mentionedItems);
 		}