Bug 140542 label can't be displayed without resource file or unmatched key
Steps to reproduce: 1.New a report, add a lable with text "aaa" 2.Add a resource file for the report, set key to "key1", value to "actuate", apply the value to the label 3.Clear the resource file in Property Editor->General->Resource File (or change the key to "abc") 4.Preview the report Expected result: 1.Display label text "aaa" on preview or 2.Give a warning message to say resource file is not found or unmatched key Actual result: Nothing displays on preview
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/core/Module.java
if ( !attributeListeners.contains( listener ) )
			attributeListeners.add( listener );
	}
	/**
	 * Removes one attribute listener. If the listener not registered, then the
	 * request is silently ignored.
	 * 
	 * @param listener
	 *            the attribute listener to remove
	 * @return <code>true</code> if <code>listener</code> is successfully
	 *         removed. Otherwise <code>false</code>.
	 * 
	 */
	public boolean removeAttributeListener( IAttributeListener listener )
	{
		if ( attributeListeners == null )
			return false;
		return attributeListeners.remove( listener );
	}
	/**
	 * Broadcasts the file name event to the file name listeners.
	 * 
	 * @param event
	 *            the file name event
	 */
	public void broadcastFileNameEvent( AttributeEvent event )
	{
		if ( attributeListeners != null )
		{
			Iterator iter = attributeListeners.iterator( );