[#597] Addressing code review comments pt 1.

Author: nikagra

core/src/main/java/com/datastax/oss/driver/internal/core/channel/ChannelFactory.java

@@ -257,7 +257,7 @@ private void connect(
         cf -> {
           if (connectFuture.isSuccess()) {
             Channel channel = connectFuture.channel();
-            DriverChannel driverChannel = // driver channel init
+            DriverChannel driverChannel =
                 new DriverChannel(endPoint, channel, context.getWriteCoalescer(), currentVersion);
             // If this is the first successful connection, remember the protocol version and
             // cluster name for future connections.

core/src/main/java/com/datastax/oss/driver/internal/core/channel/ProtocolInitHandler.java

@@ -435,6 +435,13 @@ private void maybeSwitchToModernFraming() {
     }
   }
 
+  /**
+   * If <code>SCYLLA_USE_METADATA_ID</code> feature was negotiated we need to replace {@link
+   * FrameEncoder} and {@link FrameDecoder} handlers with instances aware of a negotiated protocol
+   * feature.
+   *
+   * @param metadataIdEnabled indicates if feature is successfully negotiated
+   */
   private void maybeUpdatePipelineWithProtocolOptions(boolean metadataIdEnabled) {
     if (metadataIdEnabled) {
       ProtocolFeatures protocolFeatures =