tds/src/main/java/thredds/core/TdsRequestedDataset.java
public static GridDataset getGridDataset(HttpServletRequest request, HttpServletResponse response, String path) throws IOException {
    TdsRequestedDataset trd = new TdsRequestedDataset(request, null);
    if (path != null) trd.path = path;
    return trd.openAsGridDataset(request, response);
  }
public static GridDataset getGridDataset(HttpServletRequest request, HttpServletResponse response, String path) throws IOException {
    TdsRequestedDataset trd = new TdsRequestedDataset(request, null);
    if (path != null) trd.path = path;
    return trd.openAsGridDataset(request, response);
  }
return null means request has been handled, and calling routine should exit without further processing