code: @Override
    public void dispose() {
      if (sspiContext != null) {
        sspiContext.dispose();
        sspiContext = null;
      }
      if (clientCredentials != null) {
        clientCredentials.dispose();
        clientCredentials = null;
      }
    }
docs: Clean up native win32 resources after completion or failure of SSPI authentication. This
  SSPIClient instance becomes unusable after disposal.