docs: public String getDiffHtml() throws Exception {
  
          CmsDiffViewMode mode = "all".equals(m_diffMode) ? CmsDiffViewMode.ALL : CmsDiffViewMode.DIFF_ONLY;
          String text1 = m_text1;
          String text2 = m_text2;
          if ("text".equals(m_textMode)) {
              text1 = CmsHtml2TextConverter.html2text(text1, "UTF-8");
              text2 = CmsHtml2TextConverter.html2text(text2, "UTF-8");
          }
          CmsHtmlDifferenceConfiguration conf = new CmsHtmlDifferenceConfiguration(
              mode == CmsDiffViewMode.ALL ? -1 : 2,
              A_CmsUI.get().getLocale());
          String diff = Diff.diffAsHtml(text1, text2, conf);
          String html = null;
          if (CmsStringUtil.isNotEmpty(diff)) {
              html = diff;
          } else {
              html = wrapLinesWithUnchangedStyle(
                  CmsStringUtil.substitute(CmsStringUtil.escapeHtml(m_text1), "<br/>", ""));
          }
          return html;
  
      }