var promise = new Promise<Release>((resolve, reject) => {
     let httpClient: httpc.HttpClient = new httpc.HttpClient(userAgent, [handler]);
     let taggedReleaseUrl = "https://api.github.com/repos/" + repositoryName + "/releases/tags/" + tag;
     taggedReleaseUrl = taggedReleaseUrl.replace(/([^:]\/)\/+/g, "$1");
     httpClient.get(taggedReleaseUrl).then((res) => {
         res.readBody().then((body) => {
             let response = JSON.parse(body);
             let release: Release = {
                 Id: response["id"],
                 Name: response["tag_name"]
             }
             resolve(release);
         });
     }, (reason) => {
         reject(reason);
     });
 });

    // make a request to the endpoint uri, and take a look at the response header to
    // determine whether this is our service, or an external service.
    private static async isEndpointInternal(endpointUri: string): Promise<boolean> {
        let requestOptions: IRequestOptions;
        try {
            const proxy = tl.getHttpProxyConfiguration();
            requestOptions = proxy ? { proxy } : {};
        } catch (error) {
            tl.debug('unable to determine proxy configuration: ' + error);
            requestOptions = {};
        }

        const headers: IHeaders = {};
        headers['X-TFS-FedAuthRedirect'] = 'Suppress';

        const endpointClient = new HttpClient(tl.getVariable('AZURE_HTTP_USER_AGENT'), null, requestOptions);
        try {
            const resp = await endpointClient.get(endpointUri, headers);
            return resp.message.rawHeaders !== null && resp.message.rawHeaders.some( t => t.toLowerCase().indexOf('x-tfs') >= 0 || t.toLowerCase().indexOf('x-vss') >= 0 );
        } catch (error) {
            tl.debug(error);
            return false;
        }
    }