code: function GrantManager (config) {
    this.realmUrl = config.realmUrl;
    this.clientId = config.clientId;
    this.secret = config.secret;
    this.publicKey = config.publicKey;
    this.public = config.public;
    this.bearerOnly = config.bearerOnly;
    this.notBefore = 0;
    this.rotation = new Rotation(config);
  }
docs: Construct a grant manager.
  
  @param {Config} config Config object.
  
  @constructor