public static string GetClaAccessInvoiceNumber(DefaultContext db)
{
string newInvoiceNumberValue;
lock (LockClaAccessInvoiceNumber)
{
string invoiceNumberValue = GetPropertiesBagItem(db, ClaAccessInvoiceNumberKey);
var invoiceNumber = new InvoiceNumber(invoiceNumberValue);
newInvoiceNumberValue = invoiceNumber.Next();
SavePropertiesBagItem(db, ClaAccessInvoiceNumberKey, newInvoiceNumberValue, false);
}
return newInvoiceNumberValue;
}