TextFacet textfacet = MultifacetedBrowsing.getMfb(request).getTextFacetById(request.getParameter("facetId"));
AjaxXmlBuilder builder = new AjaxXmlBuilder();
Collection<String> values = textfacet.listMatching(request.getParameter("substring"));
for(String key : values){
builder.addItem(key, key);
}
return builder.toString();
}