public static void closeClient(InetSocketAddress address) {
        Client client = CLIENT_MAP.remove(address);
        Optional.ofNullable(client)
                .ifPresent(c -> {
                    try {
                        c.close();
                    } catch (IOException e) {
                        throw new OperationException(e);
                    }
                });
    }
@Test
    public void closeTest() throws IOException {
        InetSocketAddress address = InetSocketAddress.createUnresolved(addressStr, port.getPort());
        ChannelPoolHandler channelPoolHandler = new ClientPoolHandler(new ClientTakeHandler());
        ClientConnection clientConnection = new SimpleClientConnection(address, channelPoolHandler);
        RPCClient rpcClient = new RPCClient(clientConnection);

        ClientSupport.closeClient(new InetSocketAddress(addressStr, port.getPort()));
        rpcClient.close();
    }