code: public static boolean isGz(String fName)
    {
      if (Strings.isNullOrEmpty(fName)) {
        return false;
      }
      return fName.endsWith(GZ_SUFFIX) && fName.length() > GZ_SUFFIX.length();
    }
docs: Checks to see if fName is a valid name for a "*.gz" file
  
  @param fName The name of the file in question
  
  @return True if fName is a properly named .gz file, false otherwise