code: public void setProxyIoSession(ProxyIoSession proxyIoSession) {
          if (proxyIoSession == null) {
              throw new NullPointerException("proxySession object cannot be null");
          }
  
          if (proxyIoSession.getProxyAddress() == null) {
              throw new NullPointerException(
                      "proxySession.proxyAddress cannot be null");
          }
  
          proxyIoSession.setConnector(this);
          setDefaultRemoteAddress(proxyIoSession.getProxyAddress());
          this.proxyIoSession = proxyIoSession;
      }
docs: Sets the proxy session object of this connector.
  @param proxyIoSession the configuration of this connector.