success set on users add to group

src/main/java/org/gcube/data/access/storagehub/services/GroupManager.java

@@ -402,6 +402,7 @@ public class GroupManager {
 			this.internalAddUserToGroup(session, group, user);
 
 			session.save();
+			success = true;
 		}catch(StorageHubException she ){
 			log.error(she.getErrorMessage(), she);
 			GXOutboundErrorResponse.throwException(she, Response.Status.fromStatusCode(she.getStatus()));