How to use the botframework-connector.TokenApiClient function in botframework-connector

protected createTokenApiClient(serviceUrl: string): TokenApiClient {
        const client = new TokenApiClient(this.credentials, { baseUri: serviceUrl, userAgent: USER_AGENT });
        return client;
    }

protected createTokenApiClient(serviceUrl: string): TokenApiClient {
        const client = new TokenApiClient(this.credentials, { baseUri: serviceUrl, userAgent: USER_AGENT });
        return client;
    }

constructor({appId: appId, password: password, fb_verify_token: fb_verify_token, fb_password: fb_password, fb_access_token: fb_access_token}){
        super({
            verify_token: fb_verify_token,
            app_secret: fb_password,
            access_token: fb_access_token
       });

       this.credentials = new botframework_connector.MicrosoftAppCredentials(appId, password);
       this.credentialsProvider = new botframework_connector.SimpleCredentialProvider(appId, password);
       this.tokenApiClient = new botframework_connector.TokenApiClient(this.credentials, { baseUri: OAUTH_ENDPOINT, userAgent: exports.USER_AGENT });;
    }