code: public void addSummaryComment(Element element, List<? extends DocTree> firstSentenceTags, Content htmltree) {
          addCommentTags(element, firstSentenceTags, false, true, htmltree);
      }
docs: Adds the summary content.
  
  @param element the Element for which the summary will be generated
  @param firstSentenceTags the first sentence tags for the doc
  @param htmltree the documentation tree to which the summary will be added