import { SPHttpClient, SPHttpClientResponse, ISPHttpClientOptions} from '@microsoft/sp-http';
    
    @override
      public onInit(): Promise<void> {
        Log.info(LOG_SOURCE, `Initialized ${strings.Title}`);
    
        let message: string = this.properties.testMessage;
        if (!message) {
          message = '(No properties were provided.)';
        }
        let currentWebUrl = this.context.pageContext.web.absoluteUrl;
        let requestUrl = currentWebUrl.concat("/_api/web?$select=AllProperties&$expand=AllProperties")
        this.context.spHttpClient.get(requestUrl, SPHttpClient.configurations.v1)
            .then((response: SPHttpClientResponse) => {
                if (response.ok) {
                    response.json().then((responseJSON) => {
                        if (responseJSON!=null){
                              console.log(responseJSON.AllProperties.GroupType);
                        }
                    });
                }
            });
        Dialog.alert(`Hello from ${strings.Title}:\n\n${message}`);
    
    
        return Promise.resolve();
      }