code: function crumbIssuer(jenkins, callback) {
    jenkins.crumbIssuer.get(function(err, data) {
      if (err) return callback(err);
      if (!data || !data.crumbRequestField || !data.crumb) {
        return callback(new Error('Failed to get crumb'));
      }
  
      callback(null, {
        headerName: data.crumbRequestField,
        headerValue: data.crumb,
      });
    });
  }
docs: Default crumb issuser