Bug 168026 Still use the existing data binding even though the aggregate is different
I had a table in which a data binding which aggregates on a group. When I insert a new data item in the report, although the expressions are same, it aggregates on All, then it refered to the existing data binding. The expected behavior would be a new data binding is created with different aggregates.
model/org.eclipse.birt.report.model.tests/test/org/eclipse/birt/report/model/api/ReportItemHandleTest.java
* @throws Exception
	 *             if any exception
	 */
	public void testUndoInvalidDataSet( ) throws Exception
	{
		TextItemHandle textHandle = (TextItemHandle) designHandle
				.findElement( "myText" ); 
		textHandle.setProperty( ReportItem.DATA_SET_PROP, "myDataSet" ); 
		designHandle.getCommandStack( ).undo( );
		assertEquals( "unknownDataSet", textHandle 
				.getStringProperty( ReportItem.DATA_SET_PROP ) );
		assertEquals( null, textHandle
				.getElementProperty( ReportItem.DATA_SET_PROP ) );
		assertEquals( null, textHandle.getDataSet( ) );
	}
	/**
	 * Tests the special "vertical-align" properties of report items that reside
	 * in cells.
	 * 
	 * @throws Exception
	 */
	public void testCssProperties( ) throws Exception
	{
		
		LabelHandle label = (LabelHandle) designHandle
				.findElement( "nested label1" ); 
		assertEquals( DesignChoiceConstants.VERTICAL_ALIGN_TOP, label
				.getProperty( Style.VERTICAL_ALIGN_PROP ) );
		label = (LabelHandle) designHandle.findElement( "nested label2" ); 
		assertEquals( DesignChoiceConstants.VERTICAL_ALIGN_BOTTOM, label