code: private void addDefaultsIfNeeded(ServletRequest req)
              throws JspException
      {
          if (_defaultSelections != null) {
              Iterator iterator = _defaultSelections.iterator();
              while (iterator.hasNext()) {
                  Object selection = iterator.next();
                  if (!_optionList.contains(selection)) {
                      addOption(req, selection.toString(), selection.toString());
                  }
              }
          }
      }
docs: add the default values specified in the tag if they are needed.