@Override
    protected SSLEngine createEngine(SSLEngineFactory factory) {
        if (mSSLEngine == null) {
            mSSLEngine = super.createEngine(factory);
            if (mSSLEngine != null && mClientAlpns != null) {
                enableAlpn();
            }
        }
        return mSSLEngine;
    }
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