assertGetThumbnailUrl(data, expected);

        data = "<meta property=\"og:image\" content=\"/foo.jpg\" />";
        expected = "http://example.com/foo.jpg";
        assertGetThumbnailUrl(data, expected);

        data = "<img src=\"http://example/foo.jpg\">";
        expected = "http://example/foo.jpg";
        assertGetThumbnailUrl(data, expected);

        data = "<img src=\"http://example/foo.jpg\">" //

        if (path.endsWith(".png")) {
            return "image/png";
        }
        if (path.endsWith(".gif")) {
            return "image/gif";
        }
        if (path.endsWith(".jpg") || path.endsWith(".jpeg")) {
            return "image/jpeg";
        }
        return "application/octet-stream";
    }

            });
            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);

            generator.saveImage(input, outputFile);
        }
        assertImageSize(outputFile, 100, 66);

        imagePath = "thumbnail/600x400.jpg";
        try (ImageInputStream input = ImageIO.createImageInputStream(classLoader.getResourceAsStream(imagePath))) {
            generator.saveImage(input, outputFile);
        }
        assertImageSize(outputFile, 100, 66);

    Buffer result = new Buffer();
    result.writeAll(Okio.source(file));
    return result;
  }

  private String contentType(String path) {
    if (path.endsWith(".png")) return "image/png";
    if (path.endsWith(".jpg")) return "image/jpeg";
    if (path.endsWith(".jpeg")) return "image/jpeg";
    if (path.endsWith(".gif")) return "image/gif";
    if (path.endsWith(".html")) return "text/html; charset=utf-8";

    /** The key of the configuration. e.g. css */
    String SUPPORTED_UPLOADED_CSS_EXTENTIONS = "supported.uploaded.css.extentions";

    /** The key of the configuration. e.g. jpg,jpeg,gif,png,swf */
    String SUPPORTED_UPLOADED_MEDIA_EXTENTIONS = "supported.uploaded.media.extentions";

    /** The key of the configuration. e.g. license.properties */

    public static final String LABELS_facet_filetype_tiff = "{labels.facet_filetype_tiff}";

    /** The key of the message: JPEG Image */
    public static final String LABELS_facet_filetype_jpg = "{labels.facet_filetype_jpg}";

    /** The key of the message: Archive */
    public static final String LABELS_facet_filetype_archive = "{labels.facet_filetype_archive}";

    /** The key of the message: Batch File */