Future-proof HTTPS endpoint identification (#2104)

Netty 4.2 changes the default for hostname verification for TLS clients,
so that it is now enabled by default.

As a result, clients that rely on the default being _off_ will find
themselves unable to disable it.

Instead, clients should explicitly configure their desired endpoint
identification algorithm in all cases.

Since Netty 4.1.112 we also have a convenient method on the
`SslContextBuilder` for doing this, so we don't need multiple
round-trips through `SSLParameters`.

This PR changes the `DefaultSslEngineFactory` to make use of this
method, so it always configures the endpoint identification algorithm to
match the desired setting of
`AsyncHttpClientConfig..isDisableHttpsEndpointIdentificationAlgorithm()`.

Author: chrisvest

client/src/main/java/org/asynchttpclient/netty/ssl/DefaultSslEngineFactory.java

@@ -58,6 +58,9 @@ private SslContext buildSslContext(AsyncHttpClientConfig config) throws SSLExcep
             sslContextBuilder.trustManager(InsecureTrustManagerFactory.INSTANCE);
         }
 
+        sslContextBuilder.endpointIdentificationAlgorithm(
+                config.isDisableHttpsEndpointIdentificationAlgorithm() ? "" : "HTTPS");
+
         return configureSslContextBuilder(sslContextBuilder).build();
     }
 

client/src/main/java/org/asynchttpclient/netty/ssl/SslEngineFactoryBase.java

@@ -19,7 +19,6 @@
 import org.asynchttpclient.SslEngineFactory;
 
 import javax.net.ssl.SSLEngine;
-import javax.net.ssl.SSLParameters;
 
 public abstract class SslEngineFactoryBase implements SslEngineFactory {
 
@@ -30,10 +29,5 @@ protected String domain(String hostname) {
 
     protected void configureSslEngine(SSLEngine sslEngine, AsyncHttpClientConfig config) {
         sslEngine.setUseClientMode(true);
-        if (!config.isDisableHttpsEndpointIdentificationAlgorithm()) {
-            SSLParameters params = sslEngine.getSSLParameters();
-            params.setEndpointIdentificationAlgorithm("HTTPS");
-            sslEngine.setSSLParameters(params);
-        }
     }
 }