code: private List<ConfigurationHelper.ConfigurationInfo<String>>
        getFilePathConfigurationListWithDefault(@Nullable List<String> filePaths,
         String defaultFilePath) {
      List<ConfigurationHelper.ConfigurationInfo<String>> defaultConfigList =
          ConfigurationHelper.newList(true, defaultFilePath);
      List<ConfigurationHelper.ConfigurationInfo<String>> filePathConfigList =
          ConfigurationHelper.newList(filePaths, true);
      if (defaultConfigList != null) {
        if (filePathConfigList == null) {
          filePathConfigList = defaultConfigList;
        } else {
          filePathConfigList.addAll(defaultConfigList);
        } 
      }
      return filePathConfigList;
    }
docs: Gets a combined configuration list with the default added last so that
  {@code filePaths} will override {@code defaultFilePath}.