code: function getFilesFromAssets(assets) {
    let files = []
  
    Object.keys(assets).forEach((key) => {
      const asset = assets[key]
  
      if (asset.emitted && fs.existsSync(asset.existsAt)) {
        const source = asset.source()
        const assetSource = Array.isArray(source) ? source.join('\n') : source
        const assetHash = createHash('sha256').update(assetSource).digest('hex')
  
        // new file, or existing one that changed
        if (!assetsHash[key] || assetsHash[key] !== assetHash) {
          files = [...files, asset.existsAt.replace(config.paths.dist, '')]
          assetsHash[key] = assetHash
        }
      }
    })
  
    return files
  }
docs: Return an array of changed files that have been written to the file system.
  Uses the same method as write-file-webpack-plugin to determine which files
  have changed.
  @see https://github.com/gajus/write-file-webpack-plugin/blob/master/src/index.js#L134-L145
  
  @param   assets  Object   Assets obejct from webpack stats.compilation object
  @return          Array