diff --git a/wise-webapp/src/main/java/com/wisemapping/model/Collaboration.java b/wise-webapp/src/main/java/com/wisemapping/model/Collaboration.java
index 79a06344..42395542 100644
--- a/wise-webapp/src/main/java/com/wisemapping/model/Collaboration.java
+++ b/wise-webapp/src/main/java/com/wisemapping/model/Collaboration.java
@@ -1,20 +1,20 @@
 /*
-*    Copyright [2015] [wisemapping]
-*
-*   Licensed under WiseMapping Public License, Version 1.0 (the "License").
-*   It is basically the Apache License, Version 2.0 (the "License") plus the
-*   "powered by wisemapping" text requirement on every single page;
-*   you may not use this file except in compliance with the License.
-*   You may obtain a copy of the license at
-*
-*       http://www.wisemapping.org/license
-*
-*   Unless required by applicable law or agreed to in writing, software
-*   distributed under the License is distributed on an "AS IS" BASIS,
-*   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-*   See the License for the specific language governing permissions and
-*   limitations under the License.
-*/
+ *    Copyright [2015] [wisemapping]
+ *
+ *   Licensed under WiseMapping Public License, Version 1.0 (the "License").
+ *   It is basically the Apache License, Version 2.0 (the "License") plus the
+ *   "powered by wisemapping" text requirement on every single page;
+ *   you may not use this file except in compliance with the License.
+ *   You may obtain a copy of the license at
+ *
+ *       http://www.wisemapping.org/license
+ *
+ *   Unless required by applicable law or agreed to in writing, software
+ *   distributed under the License is distributed on an "AS IS" BASIS,
+ *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *   See the License for the specific language governing permissions and
+ *   limitations under the License.
+ */
 
 package com.wisemapping.model;
 
@@ -29,22 +29,24 @@ public class Collaboration implements Serializable {
 
     @Id
     @GeneratedValue(strategy = GenerationType.IDENTITY)
-    private int id;;
+    private int id;
+    ;
 
-    @Column(name = "role_id",unique = true,nullable = true)
+    @Column(name = "role_id", unique = true)
     private CollaborationRole role;
 
     @ManyToOne
-    @JoinColumn(name="mindmap_id",nullable = false)
+    @JoinColumn(name = "mindmap_id", nullable = false)
     private Mindmap mindMap;
 
     @ManyToOne(fetch = FetchType.LAZY)
-    @JoinColumn(name="colaborator_id",nullable = false)
+    @JoinColumn(name = "colaborator_id", nullable = false)
     private Collaborator collaborator;
 
     @ManyToOne(cascade = CascadeType.ALL)
-    @JoinColumn(name="properties_id",nullable = false, unique = true)
-    private CollaborationProperties collaborationProperties =  new CollaborationProperties();;
+    @JoinColumn(name = "properties_id", nullable = false, unique = true)
+    private CollaborationProperties collaborationProperties = new CollaborationProperties();
+    ;
 
     public Collaboration() {
     }
@@ -129,10 +131,9 @@ public class Collaboration implements Serializable {
 
     @Override
     public int hashCode() {
-        int result = (int) (id ^ (id >>> 32));
+        int result = id ^ (id >>> 32);
         result = 31 * result + (role != null ? role.hashCode() : 0);
         result = 31 * result + (mindMap != null ? mindMap.hashCode() : 0);
-        result = 31 * result + (collaborator != null ? collaborator.hashCode() : 0);
         return result;
     }
 }