code: public MessageBuilder addFileAsSpoiler(BufferedImage image, String fileName) {
          delegate.addFile(image, "SPOILER_" + fileName);
          return this;
      }
docs: Adds a file to the message and marks it as spoiler.
  
  @param image The image to add as an attachment.
  @param fileName The file name of the image.
  @return The current instance in order to chain call methods.
  @see #addAttachmentAsSpoiler(BufferedImage, String)