@UiChild(tagname = "loadingIndicator", limit = 1)
    public void setLoadingIndicator(Widget widget) {
        loadingIndicator = widget;
    }
Set the widget to display when the data is loading.

@param widget the loading indicator, or null to disable
stroom-core-client-widget/src/main/java/com/google/gwt/user/cellview/client/AbstractCellTable.java