#503 fix the "fin_close" problem

src/main/java/com/corundumstudio/socketio/transport/WebSocketTransport.java

@@ -19,6 +19,8 @@ import java.util.List;
 import java.util.UUID;
 import java.util.concurrent.TimeUnit;
 
+import com.corundumstudio.socketio.protocol.Packet;
+import com.corundumstudio.socketio.protocol.PacketType;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -138,12 +140,17 @@ public class WebSocketTransport extends ChannelInboundHandlerAdapter {
 
     @Override
     public void channelInactive(ChannelHandlerContext ctx) throws Exception {
-        ClientHead client = clientsBox.get(ctx.channel());
+        final  Channel channel = ctx.channel();
+        ClientHead client = clientsBox.get(channel);
+        Packet packet = new Packet(PacketType.MESSAGE);
         if (client != null && client.isTransportChannel(ctx.channel(), Transport.WEBSOCKET)) {
             log.debug("channel inactive {}", client.getSessionId());
             client.onChannelDisconnect();
         }
         super.channelInactive(ctx);
+        client.send(packet);
+        channel.close();
+        ctx.close();
     }
 
     private void handshake(ChannelHandlerContext ctx, final UUID sessionId, String path, FullHttpRequest req) {