code: protected void appendAttribute(StringBuilder sb, Attr aNode) {
          sb.append("<").append(aNode.getOwnerElement().getNodeName());
          sb.append(' ')
              .append(aNode.getNodeName()).append("=\"")
              .append(aNode.getNodeValue()).append("\"...>");
      }
docs: Formats a placeholder for an attribute for {@link #getShortString}.
  
  @param sb the builder to append to
  @param aNode the attribute
  
  @since XMLUnit 2.4.0