code: function(params) {
                  params = params || {};
                  params.claims = params.claims || {};
  
                  if (params.jwt) {
                      return params.jwt;
                  }
  
                  var secret = params.secret || this.driver.config.get('clientSecret');
                  params.claims.iss = params.claims.iss || this.driver.config.get('clientId');
                  params.claims.aud = params.claims.aud || this.driver.config.get('audience', corbel.Iam.AUD);
                  params.claims.scope = params.claims.scope || this.driver.config.get('scopes', '');
                  return corbel.jwt.generate(params.claims, secret);
              }
docs: Build a JWT with default driver config
  @param  {Object} params
  @param  {String} [params.secret]
  @param  {Object} [params.claims]
  @param  {String} [params.claims.iss]
  @param  {String} [params.claims.aud]
  @param  {String} [params.claims.scope]
  @return {String} JWT assertion