code: public static boolean isZip(final String filename)
  	{
  		for (final String element : FileConst.ZIP_EXTENSIONS)
  		{
  			if (filename.endsWith(element))
  			{
  				return true;
  			}
  		}
  		return false;
  	}
docs: Checks if the given filename is a zip-file.
  
  @param filename
  The filename to check.
  @return True if the filename is a zip-file otherwise false.