code: function (asset) {
      var bundle = this.bundle;
      var requires = bundle.getRequiredFiles(asset.assetFilePath);
      if (requires.length > 0) {
        return requires.map(function (file) {
          return bundle.getAsset(file).logicalPath;
        });
      } else {
        return [asset.logicalPath];
      }
    }
docs: Get a list of logical paths that the specified asset
  "requires" (i.e. should be comprised of if the file is being merged together)