code: @Override
      public AzureAdAccessToken acquireAccessToken() throws Exception {
          AuthenticationResult authResult = getToken().get();
          return new AzureAdAccessToken(authResult.getAccessToken(), authResult.getExpiresOnDate());
      }
docs: Acquires an access token
  @see com.microsoft.windowsazure.services.media.authentication.TokenProvider#acquireAccessToken()