public static HeaderType AddSubHeaderTableContent(this HeaderType header, string headerText, TableType tableContent)
 {
     if(header == null)
         throw new ArgumentNullException("header");
     HeaderType subHeader = new HeaderType
     {
         text = headerText,
         level = header.level + 1,
     };
     subHeader.AddHeaderTableContent(tableContent);
     header.AddSubHeader(subHeader);
     return subHeader;
 }
        public static void AddHeaderTableContent(this HeaderType header, TableType tableContent)
        {
            if (header == null)
                throw new ArgumentNullException("header");
            ParagraphType[] content = (header.Paragraph ?? new ParagraphType[0]).Union(
                new ParagraphType[]
                    {
                        new ParagraphType
                            {
                                Item = tableContent
                            }

                    }).ToArray();
            header.Paragraph = content;
        }