ContactCellList ccl = new ContactCellList();
RootPanel.get("contactCellList").add(ccl);
TooltipOptions options = new TooltipOptions();
//provide dynamic content
options.withContent(new TooltipContentProvider() {
@Override
public String getContent(Element element) {
Integer id = Integer.parseInt(element.getAttribute("data-contact-id"));
ContactInfo contact = ContactDatabase.get().queryContactById(id);