private String getConscryptEngineAlpn() throws NoSuchMethodException, IllegalAccessException,
            InvocationTargetException {
        Method getAlpnSelectedProtocolMethod = mSSLEngine.getClass().getDeclaredMethod(
                "getAlpnSelectedProtocol");
        getAlpnSelectedProtocolMethod.setAccessible(true);
        byte[] selectedProtocol = (byte[]) getAlpnSelectedProtocolMethod.invoke(mSSLEngine);
        return selectedProtocol != null ? new String(selectedProtocol, Charset.forName("UTF-8")) : null;
    }
Http SSL codec enables Application-Layer Protocol Negotiation(ALPN).

See http://tools.ietf.org/html/draft-agl-tls-nextprotoneg-04#page-4

@author Megatron King
@since 2019/1/3 23:31
netbare-core/src/main/java/com/github/megatronking/netbare/http/HttpSSLResponseCodec.java