public static SslProvider chooseSslProvider() {
        // Use openssl only if available and has ALPN support (ie. version > 1.0.2).
        SslProvider sslProvider;
        if (ALLOW_USE_OPENSSL.get() && OpenSsl.isAvailable() && SslProvider.isAlpnSupported(SslProvider.OPENSSL)) {
            sslProvider = SslProvider.OPENSSL;
        } else {
            sslProvider = SslProvider.JDK;
        }
        return sslProvider;
    }
This function is meant to call the correct overload of {@code SslContextBuilder.forServer()}.  It should not
apply any other customization.
zuul-core/src/main/java/com/netflix/zuul/netty/ssl/BaseSslContextFactory.java