protected void encodePlaceholder(FacesContext context, Toolbar component) throws IOException {
        ResponseWriter writer = context.getResponseWriter();
        writer.startElement("div", component);
        writer.writeAttribute("id", component.getClientId(context), "id");
        writer.writeAttribute("class", "ui-toolbar-placeholder", "styleClass");
        writer.endElement("div");
    }
Check whether toolbar has a render relevant component. Separators themselves will be rendered regularly but if they are the
only components there is no need to render the toolbar.
primefaces/src/main/java/org/primefaces/component/toolbar/ToolbarRenderer.java