docs: function GitkitClient(options) {
    this.widgetUrl = options.widgetUrl;
    this.maxTokenExpiration = 86400 * 30; // 30 days
    this.audiences = [];
    if (options.projectId !== undefined) {
      this.audiences.push(options.projectId);
    }
    if (options.clientId !== undefined) {
      this.audiences.push(options.clientId);
    }
    if (this.audiences.length == 0) {
      throw new Error("Missing projectId or clientId in server configuration.");
    }
    this.authClient = new google.auth.JWT(
        options.serviceAccountEmail,
        options.serviceAccountPrivateKeyFile,
        options.serviceAccountPrivateKey,
        [GitkitClient.GITKIT_SCOPE],
        '');
    this.certificateCache = null;
    this.certificateExpiry = null;
  }