code: function s3Init(file) {
    if (file.s3) {
      return;
    }
  
    file.s3 = {};
    file.s3.headers = {};
    file.s3.path = file.path.replace(file.base, "").replace(new RegExp("\\" + path.sep, "g"), "/");
  }
docs: https://github.com/jussi-kalliokoski/gulp-awspublish-router/blob/master/lib/utils/initFile.js