code: public static Uploader createUploader(String className) throws Exception {
          Class<?> clazz = Class.forName(className);
          if (!Uploader.class.isAssignableFrom(clazz)) {
              throw new IllegalArgumentException(String.format("The class '%s' is not assignable to '%s'.",
                      className, Uploader.class.getName()));
          }
  
          return (Uploader) clazz.newInstance();
      }
docs: Create an Uploader from its fully qualified class name.
  
  The class passed in by name must be assignable to Uploader.
  See the secor.upload.class config option.
  
  @param className     The class name of a subclass of Uploader
  @return an UploadManager instance with the runtime type of the class passed by name
  @throws Exception on error