this.height = 1 + Math.max(height(left), height(right));
    }

    private void recompute() {
      recomputeMultiset();
      recomputeHeight();
    }

    private AvlNode<E> rebalance() {
      switch (balanceFactor()) {
        case -2:
          // requireNonNull is safe because right must exist in order to get a negative factor.
          requireNonNull(right);
          if (right.balanceFactor() > 0) {

                final int width = reader.getWidth(0);
                final int height = reader.getHeight(0);
                if (width <= 0 || height <= 0) {
                    return Result.NO_IMAGE;
                }
                if (!fessConfig.validateThumbnailSize(width, height)) {
                    return Result.INVALID_SIZE;
                }

    }

    private void assertImageSize(File file, int width, int height) throws IOException {
        BufferedImage img = ImageIO.read(file);
        logger.debug("width: {}, height: {}", img.getWidth(), img.getHeight());
        assertEquals("Image Width", width, img.getWidth());
        assertEquals("Image Height", height, img.getHeight());
    }

      this.height = 1 + Math.max(height(left), height(right));
    }

    private void recompute() {
      recomputeMultiset();
      recomputeHeight();
    }

    private AvlNode<E> rebalance() {
      switch (balanceFactor()) {
        case -2:
          // requireNonNull is safe because right must exist in order to get a negative factor.
          requireNonNull(right);
          if (right.balanceFactor() > 0) {

        data = "<img src=\"http://example/foo.jpg\" width=\"x\" height=\"x\">";
        assertNull(transformer.getThumbnailUrl(responseData, getDocument(data)));

        data = "<img src=\"http://example/foo.jpg\" width=\"10\" height=\"100\">";
        assertNull(transformer.getThumbnailUrl(responseData, getDocument(data)));

        data = "<img src=\"http://example/foo.jpg\" width=\"100\" height=\"10\">";

                final Integer height = getAttributeAsInteger(attributes, "height");
                final Integer width = getAttributeAsInteger(attributes, "width");
                if (!fessConfig.isThumbnailHtmlImageUrl(thumbnailUrl)) {
                    continue;
                }
                if (height != null && width != null) {
                    try {

  /**
   * The HTTP <a
   * href="https://wicg.github.io/responsive-image-client-hints/#sec-ch-viewport-height">{@code
   * Sec-CH-Viewport-Height}</a> header field name.
   *
   * @since 32.0.0
   */
  public static final String SEC_CH_VIEWPORT_HEIGHT = "Sec-CH-Viewport-Height";
  /**
   * The HTTP <a href="https://wicg.github.io/responsive-image-client-hints/#sec-ch-dpr">{@code

    java.math.BigDecimal getThumbnailHtmlImageMaxAspectRatioAsDecimal();

    default boolean validateThumbnailSize(final int width, final int height) {
        if (width <= 0 || height <= 0 || width < getThumbnailHtmlImageMinWidthAsInteger().intValue()
                || height < getThumbnailHtmlImageMinHeightAsInteger().intValue()) {
            return false;
        }

  /**
   * The HTTP <a
   * href="https://wicg.github.io/responsive-image-client-hints/#sec-ch-viewport-height">{@code
   * Sec-CH-Viewport-Height}</a> header field name.
   *
   * @since 32.0.0
   */
  public static final String SEC_CH_VIEWPORT_HEIGHT = "Sec-CH-Viewport-Height";
  /**
   * The HTTP <a href="https://wicg.github.io/responsive-image-client-hints/#sec-ch-dpr">{@code

    /**
     * Get the value for the key 'thumbnail.html.image.min.height'. <br>
     * The value is, e.g. 100 <br>
     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     */
    String getThumbnailHtmlImageMinHeight();

    /**
     * Get the value for the key 'thumbnail.html.image.min.height' as {@link Integer}. <br>
     * The value is, e.g. 100 <br>