Bug 176450 Support link to CSS Feature(Model Part)
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/command/ComplexPropertyCommand.java
* @param ref
	 *            reference to the list into which to add the structure
	 * @param item
	 *            the structure to add to the list
	 * @throws SemanticException
	 *             if the item to add is invalid.
	 */
	public void addItem( MemberRef ref, IStructure item )
			throws SemanticException
	{
		assert ref != null;
		if ( item == null )
			return;
		PropertyDefn propDefn = ref.getPropDefn( );
		assert propDefn != null;
		assertExtendedElement( module, element, propDefn );
		if ( item.isReferencable( ) )
			assert !( (ReferencableStructure) item ).hasReferences( );
		checkListMemberRef( ref );
		checkItem( ref, item );
		List list = ref.getList( module, element );
		element.checkStructureList( module, ref.getPropDefn( ), list, item );
		ActivityStack stack = getActivityStack( );
		stack.startTrans( ModelMessages
				.getMessage( MessageConstants.ADD_ITEM_MESSAGE ) );
		makeLocalCompositeValue( ref );
		list = ref.getList( module, element );
		if ( null == list )
		{
			list = new ArrayList( );