code: private String ifEmptyUseDefault(String firstValue, String defaultValue) {
          return StringUtils.ifEmpty(firstValue, defaultValue);
      }
docs: /*public FacetListBoxWidget(String facetField, String facetTitle, String facetLabel, int visibleIntColumn) {
  this(facetField,facetTitle,facetLabel);
  this.listBox.setVisibleItemCount(visibleIntColumn);
  }