域名更换一个证书之后，不被信任

websocket连接wss，虚拟机正常，真机居然出错，
WebSocket.connect(url)一直提示错误：

HandshakeException: Handshake error in client (OS Error:
CERTIFICATE_VERIFY_FAILED: unable to get local issuer certificate(handshake.cc:393)
)

证书不被信任？
那我们来强制信任证书

//强制信任证书
    HttpClient httpClient = HttpClient();
    httpClient.badCertificateCallback = (X509Certificate cert, String host, int port){
      return true;
    };
WebSocket.connect(url,customClient: httpClient)