* URLs that represent servers, shares, or directories require a trailing slash '/'.
 * </td>
 * </tr>
 *
 * </table>
 * 
 * <p>
 * A second constructor argument may be specified to augment the URL
 * for better programmatic control when processing many files under
 * a common base. This is slightly different from the corresponding
 * <code>java.io.File</code> usage; a '/' at the beginning of the second