org.apache.dubbo.remoting.exchange.support.DefaultFuture#closeChannel doesn't work as expected since the channel instances to be compared do not have correct equals() implementation:

```java
 public static void closeChannel(Channel channel) {
        for (Map.Entry<Long, Channel> entry : CHANNELS.entrySet()) {
            if (channel.equals(entry.getValue())) { // in netty4, channel is NettyChannel, but entry.getValue() is NettyClient, equals will return false.
                DefaultFuture future = getFuture(entry.getKey());
                if (future != null && !future.isDone()) {
                    Response disconnectResponse = new Response(future.getId());
                    disconnectResponse.setStatus(Response.CHANNEL_INACTIVE);
                    disconnectResponse.setErrorMessage("Channel " +
                            channel +
                            " is inactive. Directly return the unFinished request : " +
                            future.getRequest());
                    DefaultFuture.received(channel, disconnectResponse);
                }
            }
        }
    }
```

This is the root cause of issue 1 in  #1968.
super(url, wrapChannelHandler(url, handler));
    }
    /**
     * Init bootstrap
     *
     * @throws Throwable
     */
    @Override
    protected void doOpen() throws Throwable {
        final NettyClientHandler nettyClientHandler = new NettyClientHandler(getUrl(), this);
        bootstrap = new Bootstrap();
        bootstrap.group(nioEventLoopGroup)
                .option(ChannelOption.SO_KEEPALIVE, true)
                .option(ChannelOption.TCP_NODELAY, true)
                .option(ChannelOption.ALLOCATOR, PooledByteBufAllocator.DEFAULT)
                
                .channel(NioSocketChannel.class);
        bootstrap.option(ChannelOption.CONNECT_TIMEOUT_MILLIS, Math.max(3000, getConnectTimeout()));
        bootstrap.handler(new ChannelInitializer() {
            @Override
            protected void initChannel(Channel ch) throws Exception {
                int heartbeatInterval = UrlUtils.getHeartbeat(getUrl());
                NettyCodecAdapter adapter = new NettyCodecAdapter(getCodec(), getUrl(), NettyClient.this);
                ch.pipeline()
                        .addLast("decoder", adapter.getDecoder())
                        .addLast("encoder", adapter.getEncoder())
                        .addLast("client-idle-handler", new IdleStateHandler(heartbeatInterval, 0, 0, MILLISECONDS))
                        .addLast("handler", nettyClientHandler);