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/src/org/eclipse/birt/report/model/api/ReportItemHandle.java
*            the property value to be set.
	 * @throws SemanticException
	 *             if the property is locked.
	 */
	public void setBookmark( String value ) throws SemanticException
	{
		setStringProperty( IReportItemModel.BOOKMARK_PROP, value );
	}
	/**
	 * Returns visibility rules defined on the report item. The element in the
	 * iterator is the corresponding <code>StructureHandle</code> that deal
	 * with a <code>Hide</code> in the list.
	 * 
	 * @return the iterator for visibility rules defined on this report item.
	 * 
	 * @see org.eclipse.birt.report.model.api.elements.structures.HideRule
	 */
	public Iterator visibilityRulesIterator( )
	{
		PropertyHandle propHandle = getPropertyHandle( IReportItemModel.VISIBILITY_PROP );
		assert propHandle != null;
		return propHandle.iterator( );
	}
	/**
	 * Returns the script executed when the element is created in the Factory.
	 * Called after the item is created, but before the item is saved to the
	 * report document file.
	 * 
	 * @return the script that executes
	 */