code: function addCacheHeader(asset, res, fullUrl) {
              const shouldCache = asset.cacheable && (/[0-9a-z]{40}/).test(fullUrl);
              res.setHeader('Cache-Control', shouldCache ? `max-age=${oneYearInSeconds}` : 'no-cache');
          }
docs: If the manifest defines the file as cacheable and query has a cache buster (i.e.
  hash added to it after ?) adds a Cache-Control header letting know Chrome that this
  file can be cached. If that is not the case, no-cache is passed.
  
  @param {Asset}  asset     - currently sent asset
  @param {Object} res       - response object
  @param {string} fullUrl   - url