getCacheKeyForNonLinear_(nonLinearAd) {
    return [
      nonLinearAd.adId,
      nonLinearAd.adParameters,
      nonLinearAd.adSystem,
      nonLinearAd.adTitle,
      nonLinearAd.creativeAdId,
      nonLinearAd.creativeId,
      nonLinearAd.creativeSequence,
      nonLinearAd.height,
      nonLinearAd.width,
      nonLinearAd.staticResource,
    ].join('');
  }
@param {mediaTailor.NonLinearAd} nonLinearAd
@return {string}
@private