code: public String calcDefaultContent() {
          if (defaultContentType == null) return defaultContent;
          String s;
          switch (defaultContentType) {
          case BUTTON:
              s = "<button data-role='none'>";
              if (!Empty.is(defaultContent)) s += defaultContent;
              return s + "</button>";
  
          case CHECKBOX:
          case CHECKBOX_ROWSELECT:
              s = "<input type='checkbox' data-role='none'";
              if (DefaultContentType.CHECKBOX_ROWSELECT.equals(defaultContentType)) {
                  s += " class='" + JsDataTable.CHECKBOX_ROWSEL + "'";
              }
              if (!Empty.is(defaultContent)) {
                  s += ">" + defaultContent + "</input>";
              } else {
                  s += "></input>";
              }
              return s;
  
          case ROW_DETAILS:
              return "";
  
          default:
              return defaultContent;
          }
      }
docs: Combines both defaultContentType and defaultContent and generates proper content.