code: public static String getGzBaseName(String fname)
    {
      final String reducedFname = Files.getNameWithoutExtension(fname);
      if (isGz(fname) && !reducedFname.isEmpty()) {
        return reducedFname;
      }
      throw new IAE("[%s] is not a valid gz file name", fname);
    }
docs: Get the file name without the .gz extension
  
  @param fname The name of the gzip file
  
  @return fname without the ".gz" extension
  
  @throws IAE if fname is not a valid "*.gz" file name