* <li>{@literal vfsfile} (JBossAS5 proprietary protocol, alias for {@literal file})</li>
 * <li>{@literal vfszip} (JBossAS5 proprietary protocol)</li>
 * </ul>
 *
 * @author koichik
 * @see URLUtil#toCanonicalProtocol(String)
 * @see ClassTraversalUtil
 * @see ResourceTraversalUtil
 */
public abstract class TraversalUtil {

    /**
     * Do not instantiate.
     */
    protected TraversalUtil() {
    }

     *
     * @param protocol
     *            The protocol. Must not be {@literal null} or empty.
     * @return The normalized protocol.
     */
    public static String toCanonicalProtocol(final String protocol) {
        assertArgumentNotEmpty("protocol", protocol);

        final String canonicalProtocol = CANONICAL_PROTOCOLS.get(protocol);
        if (canonicalProtocol != null) {