[netcdfgroup] How to read grib2 files using Netcdf Java API?

I know there must be a very simple way to do this, but I can't seem to find
any example or documentation.

I want to read a Grib2 file using the Java Netcdf API and tried:

File file = new File("/tmp/WRFPRS_GrbF21.grib2");  // a grib2 file
NetcdfFile ncfile = NetcdfDataset.open(file.getAbsolutePath());

but get an IOException stating: Cant read /tmp/WRFPRS_GrbF21.grib2: not a
valid NetCDF file.

I tried using ucar.dt.grid.GridDataSet.open() and got the same result.

In case it was a classpath/jar problem, I added toolsUI.jar from netcdf
2.2.22 to my classpath (has grib.jar).
Same result.  What am I missing?

thanks
Lak