internal override XObject[] ToXmlElements()
{
return(new XObject[]
{
new XElement("customerid", CustomerId),
new XElement("datecreated", DateCreated.ToXmlElements().Cast <object>()),
new XElement("datedue", DateDue.ToXmlElements().Cast <object>()),
new XElement("invoiceitems", Items.Select(item => new XElement("lineitem", item.ToXmlElements().Cast <object>()))),
});
}