code: protected void appendElement(StringBuilder sb, Element aNode) {
          sb.append("<")
              .append(aNode.getNodeName()).append("...")
              .append(">");
      }
docs: Formats a placeholder for an element for {@link #getShortString}.
  
  @param sb the builder to append to
  @param aNode the element
  
  @since XMLUnit 2.4.0