lib/classes/Utils.js/Utils/walkDirSync
class Utils:  walkDirSync(dirPath) {
    let filePaths = [];
    const list = fs.readdirSync(dirPath);
    list.forEach((filePathParam) => {
      let filePath = filePathParam;
      filePath = path.join(dirPath, filePath);
      const stat = fs.statSync(filePath);
      if (stat && stat.isDirectory()) {
        filePaths = filePaths.concat(this.walkDirSync(filePath));
      } else {
        filePaths.push(filePath);
      }
    });

    return filePaths;
  }