NetSocketInternal#writeMessage(Object) should return a Future<Void> and not be fluent

src/main/java/io/vertx/core/net/impl/NetSocketImpl.java

@@ -120,12 +120,13 @@ public class NetSocketImpl extends ConnectionBase implements NetSocketInternal {
   }
 
   @Override
-  public synchronized NetSocketInternal writeMessage(Object message) {
+  public synchronized Future<Void> writeMessage(Object message) {
     if (closed) {
       throw new IllegalStateException("Socket is closed");
     }
-    writeToChannel(message);
-    return this;
+    Promise<Void> promise = Promise.promise();
+    writeMessage(message, promise);
+    return promise.future();
   }
 
   @Override

src/main/java/io/vertx/core/net/impl/NetSocketInternal.java

@@ -14,6 +14,7 @@ package io.vertx.core.net.impl;
 import io.netty.channel.ChannelHandler;
 import io.netty.channel.ChannelHandlerContext;
 import io.vertx.core.AsyncResult;
+import io.vertx.core.Future;
 import io.vertx.core.Handler;
 import io.vertx.core.net.NetSocket;
 
@@ -56,7 +57,7 @@ public interface NetSocketInternal extends NetSocket {
    * @param message the message to write, it should be handled by one of the channel pipeline handlers
    * @return a reference to this, so the API can be used fluently
    */
-  NetSocketInternal writeMessage(Object message);
+  Future<Void> writeMessage(Object message);
 
   /**
    * Like {@link #writeMessage(Object)} but with an {@code handler} called when the message has been written