code: function walk(configDirectory, resourceName, resources) {
      resourceName = resourceName || '';
      resources = resources || {};
  
      fs.readdirSync(path.join(configDirectory, resourceName)).forEach(fileName => {
          const subResourceName = (resourceName !== '' ? resourceName + '/' : '') + fileName;
          const absoluteFilePath = path.join(configDirectory, subResourceName);
          const stat = fs.statSync(absoluteFilePath);
          if (stat && stat.isDirectory()) {
              walk(configDirectory, subResourceName, resources);
          } else if (resourceName !== '') {
              if (fileName.startsWith('config.')) {
                  if (!resources[resourceName]) resources[resourceName] = {};
                  resources[resourceName].configFile = absoluteFilePath;
              }
              if (fileName === 'index.js') {
                  if (!resources[resourceName]) resources[resourceName] = {};
                  resources[resourceName].instanceFile = absoluteFilePath;
              }
          }
      });
  
      return resources;
  }
docs: Read config files from directory recursively.
  
  @param {string} configDirectory
  @param {string} resourceName
  @param {object} resources
  @return {Array}
  @private