dataLayer.fireLayerEvent(new RowInsertEvent(dataLayer, 5));
                nattable.refresh();

	public class AddRowCommand extends AbstractRowCommand {

	    public AddRowCommand(ILayer layer, int rowPosition) {
	        super(layer, rowPosition);
	    }

	    protected AddRowCommand(AddRowCommand command) {
	        super(command);
	    }

	    @Override
	    public ILayerCommand cloneCommand() {
	        return new AddRowCommand(this);
	    }

	}
	public class AddRowCommandHandler<CellItem> implements ILayerCommandHandler<AddRowCommand> {

	    private List<CellItem> bodyData;

	    public AddRowCommandHandler(List<CellItem> bodyData) {
	        this.bodyData = bodyData;
	    }

	    @Override
	    public Class<AddRowCommand> getCommandClass() {
	        return AddRowCommand.class;
	    }

	    @Override
	    public boolean doCommand(ILayer targetLayer, AddRowCommand command) {
	        //convert the transported position to the target layer
	        if (command.convertToTargetLayer(targetLayer)) {
	            //the changed dataprovider with newly inserted element
	        	dataLayer.setDataProvider(bodyDataProvider);
	            //fire the event to refresh
	            dataLayer.fireLayerEvent(new RowInsertEvent(dataLayer, command.getRowPosition()));
	            return true;
	        }
	        return false;
	    }

	}

natTable.doCommand(new AddRowCommand(dataLayer, 1));

dataLayer.registerCommandHandler(new AddRowCommandHandler(group)) ; // group contains list of items in the table