code: public static void appendPageSectionStyleXMLToAutomaticStyle(final Header header, final XMLUtil util,
                                                                   final Appendable appendable) throws IOException {
          if (header == null) appendable.append("<style:header-style />");
          else header.appendPageSectionStyleXMLToAutomaticStyle(util, appendable);
      }
docs: Secure version of {@code pageSection.appendPageSectionStyleXMLToAutomaticStyle}: if the footer (or header) is
  null,
  then the default type is used.
  
  @param header     the footer or header, could be null
  @param util       an util to write XML data
  @param appendable the object ot which append footer/header style
  @throws IOException if footer/header style wasn't appended.