MqttTransportHandler: Use default channelReadComplete implementation to avoid memory leaks.

@@ -422,11 +422,6 @@ public class MqttTransportHandler extends ChannelInboundHandlerAdapter implement
     }
 
     @Override
-    public void channelReadComplete(ChannelHandlerContext ctx) {
-        ctx.flush();
-    }
-
-    @Override
     public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
         log.error("[{}] Unexpected Exception", sessionId, cause);
         ctx.close();