@Override
    public String call() throws ProcessException {
      Properties systemProperties = System.getProperties();

      SystemEnv.setProperties(systemProperties);

      Class<?> clazz = getClass();

      ClassLoader classLoader = clazz.getClassLoader();

      Log4JUtil.initLog4J(
          _serverId, _liferayHome, classLoader, new Log4jLogFactoryImpl(), _customLogSettings);

      try {
        LiferayPDFBoxConverter liferayConverter =
            new LiferayPDFBoxConverter(
                _inputFile,
                _thumbnailFile,
                _previewFiles,
                _extension,
                _thumbnailExtension,
                _dpi,
                _height,
                _width,
                _generatePreview,
                _generateThumbnail);

        liferayConverter.generateImagesPB();
      } catch (Exception e) {
        throw new ProcessException(e);
      }

      return StringPool.BLANK;
    }
    @Override
    public String call() throws ProcessException {
      XugglerAutoInstallHelper.installNativeLibraries();

      Class<?> clazz = getClass();

      ClassLoader classLoader = clazz.getClassLoader();

      Properties systemProperties = System.getProperties();

      SystemEnv.setProperties(systemProperties);

      Log4JUtil.initLog4J(
          _serverId, _liferayHome, classLoader, new Log4jLogFactoryImpl(), _customLogSettings);

      try {
        LiferayConverter liferayConverter =
            new LiferayVideoThumbnailConverter(
                _inputFile.getCanonicalPath(),
                _outputFile,
                _extension,
                _height,
                _width,
                _percentage);

        liferayConverter.convert();
      } catch (Exception e) {
        throw new ProcessException(e);
      }

      return StringPool.BLANK;
    }