Bug 129144 Support suppressDuplicates property on table row in report engine
See 129143 for detail. This only needs to be supported for data item in a detail row of a table.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/ir/IReportItemVisitor.java
/**
	 * visit free-form container
	 * 
	 * @param container
	 *            the free-form container to be visited
	 */
	Object visitFreeFormItem(FreeFormItemDesign container, Object value);
	/**
	 * visit list item
	 * 
	 * @param list
	 *            the list item to be viisted
	 */
	Object visitListItem(ListItemDesign list, Object value);
	/**
	 * visit text item