.fetchDirectLineToken() });

        const patchedDirectLine = {
          activity$: new Observable(observer => {
            const subscription = directLine.activity$.subscribe({
              next(activity) {
                observer.next(
                  Object.assign({}, activity, {
                    attachments: (activity.attachments || []).map(attachment =>
                      Object.assign({}, attachment, {
                        contentUrl: undefined
                      })
                