Bug 442475 - AbstractViewer not allowed to return NULL

Change-Id: Ide33068f2915d390fa4b4fa2c304c3beea134a89
Signed-off-by: Lars Vogel <Lars.Vogel@gmail.com>
diff --git a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/AbstractViewer.java b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/AbstractViewer.java
index 135fcab..95a739e 100644
--- a/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/AbstractViewer.java
+++ b/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/AbstractViewer.java
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2000, 2011 IBM Corporation and others.
+ * Copyright (c) 2000, 2014 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
@@ -7,10 +7,12 @@
  *
  * Contributors:
  *     IBM Corporation - initial API and implementation
+ *     Lars Vogel <Lars.Vogel@gmail.com> - Bug 442475
  *******************************************************************************/
 package org.eclipse.compare.internal;
 
 import org.eclipse.jface.viewers.ISelection;
+import org.eclipse.jface.viewers.StructuredSelection;
 import org.eclipse.jface.viewers.Viewer;
 
 
@@ -25,7 +27,7 @@
 	}
 	
 	public ISelection getSelection() {
-		return null;
+		return StructuredSelection.EMPTY;
 	}
 	
 	public void setSelection(ISelection s, boolean reveal) {