code: private void appendStyleMap(final XMLUtil util, final Appendable appendable) throws IOException {
          appendable.append("<style:map");
          util.appendEAttribute(appendable, "style:condition", "value()>=0");
          util.appendEAttribute(appendable, "style:apply-style-name", this.dataStyle.getName());
          appendable.append("/>");
      }
docs: Appends 16.3 style:map tag.
  
  @param util       XML util for escaping
  @param appendable where to write
  @throws IOException If an I/O error occurs