private static URLStreamHandler getDefaultStreamHandler ( String protocol ) throws IOException {
        synchronized ( PROTOCOL_HANDLERS ) {
            URLStreamHandler handler = PROTOCOL_HANDLERS.get(protocol);
            if ( handler != null )
                return handler;
            if ( factory != null ) {
                handler = factory.createURLStreamHandler(protocol);
            }
            if ( handler == null ) {

    server.setProtocols(Collections.singletonList(Protocol.H2_PRIOR_KNOWLEDGE));
    server.enqueue(new MockResponse().setBody("hello"));
    server.start();

    OkHttpClient client = new OkHttpClient.Builder()
        .socketFactory(new UnixDomainSocketFactory(socketFile))
        .protocols(Collections.singletonList(Protocol.H2_PRIOR_KNOWLEDGE))
        .build();

    Request request = new Request.Builder()

    /**
     * プロトコルを正規化して返します。
     *
     * @param protocol
     *            プロトコル。{@literal null}や空文字列であってはいけません
     * @return 正規化されたプロトコル
     */
    public static String toCanonicalProtocol(final String protocol) {
        assertArgumentNotEmpty("protocol", protocol);

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

            } else {
                url = url.replaceFirst("file:/+", systemProperties.getProperty("file.protocol.ie", "file://"));
            }
            break;
        case FIREFOX:
            if (isLocalFile) {
                url = url.replaceFirst("file:/+", systemProperties.getProperty("file.protocol.winlocal.firefox", "file://"));
            } else {

            throws IOException {
        synchronized (PROTOCOL_HANDLERS) {
            URLStreamHandler handler = (URLStreamHandler)
                    PROTOCOL_HANDLERS.get(protocol);
            if (handler != null) return handler;
            if (factory != null) {
                handler = factory.createURLStreamHandler(protocol);
            }

        }
        pkgs = System.getProperty( "java.protocol.handler.pkgs" );
        if( pkgs == null ) {
            System.setProperty( "java.protocol.handler.pkgs", "jcifs.smb1" );
        } else if( pkgs.indexOf( "jcifs.smb1" ) == -1 ) {
            pkgs += "|jcifs.smb1";
            System.setProperty( "java.protocol.handler.pkgs", pkgs );
        }
    }

     * {@link TraverserFactory}を追加します。
     *
     * @param protocol
     *            URLのプロトコル。{@literal null}や空文字列であってはいけません
     * @param factory
     *            プロトコルに対応する{@link Traverser}のファクトリ。{@literal null}であってはいけません
     */
    public static void addTraverserFactory(final String protocol, final TraverserFactory factory) {
        assertArgumentNotEmpty("protocol", protocol);
        assertArgumentNotNull("factory", factory);

    /**
     * Provides new {@link Transport} instance for given {@link RemoteRepository}, if possible.
     *
     * @throws TransportProviderException if passed in remote repository has invalid remote URL or unsupported protocol.
     */
    @Nonnull
    Transport transport(@Nonnull Session session, @Nonnull RemoteRepository repository);

    }

    /**
     * Get the protocol of the proxy server.
     *
     * @return the protocol of the proxy server
     */
    public String getProtocol() {
        return protocol;
    }

    /**
     * @param protocol the protocol of the proxy server like <i>SOCKSv4</i>
     */
    public void setProtocol(String protocol) {
        this.protocol = protocol;
    }

    }

    //    public void addProxy( String protocol, String host, int port, String username, String password,
    //                          String nonProxyHosts )
    //    {
    //        ProxyInfo proxyInfo = new ProxyInfo();
    //        proxyInfo.setHost( host );
    //        proxyInfo.setType( protocol );
    //        proxyInfo.setPort( port );