});
            task.from(extension.getCssFiles(), sub -> sub.into("css"));
            task.from(extension.getUserManual().getRoot().dir("img"), sub -> {
                sub.include("**/*.png", "**/*.gif", "**/*.jpg", "**/*.svg");
                sub.into("img");
            });
            task.from(extension.getUserManual().getResources());

            task.from(generateDocinfo);

    private volatile boolean generating;

    private Thread thumbnailQueueThread;

    protected int thumbnailPathCacheSize = 10;

    protected String imageExtention = "png";

    protected int splitSize = 10;

    protected int thumbnailTaskQueueSize = 10000;

    protected int thumbnailTaskBulkSize = 100;

    protected long thumbnailTaskQueueTimeout = 10 * 1000L;

  public static final MediaType ICO = createConstant(IMAGE_TYPE, "vnd.microsoft.icon");
  public static final MediaType JPEG = createConstant(IMAGE_TYPE, "jpeg");
  public static final MediaType PNG = createConstant(IMAGE_TYPE, "png");

  /**
   * The Photoshop File Format ({@code psd} files) as defined by <a
   * href="http://www.iana.org/assignments/media-types/image/vnd.adobe.photoshop">IANA</a>, and